AFTER A LIFETIME of buying art and architecture, former vice president Nelson Rockfeller is now selling it-with all the money, energy and enthusiasm he once put into building his collection. His latest enterprises include:

"The Nelson Rockefeller Collection," a line of about 100 reproductions of China, furniture and art objects reproduced from the originals he owns. The reproductions are selling for$75 to $7,500. Rockefeller plans to issue 100 new reproductions each year. He is paying the artists and their estates (where known) a 5 percent royalty on each sale. Hugh Morrow, his spokesman, said by telephone from New York, "He could win or lose a lot of money on this venture."

An auction of furniture, art works and objects of art from his Washington, New York and Seal Harbor, Maine, residences at Sotheby Park Bernet in New York City Oct. 6 and 7.

The recent sale of his Washington estate for $5.5 million. He also has his Seal Harbor estate up for sale for $1 million. (The real estate agent, Sotheby Parke Bernet International, reports prospective buyers are flying in every day by helicopter.)

A book on his primitive art collection. It is to be published at the end of this month, the first of five art books on aspects of his extensive collections. The photographs are by Lee Boltin, who is also the photographer for the lavish fullcolor photographs in the catalogue that offers the Rockefeller reproductions for sale.

Some 500,000 of the Rockefeller catalogues have been mailed-350,000 by Neiman-Marcus, the rest to Rockefeller's private lists.

The objects are only on exhibit at the Neiman-Marcus store in Dallas. But Murrow says there is a stockpile of the reproductions-some are in a limited edition. "We've already had hundreds of sales, though the catalogues have just gone out."

Rockefeller's venture into the reproduction business follows the lead of the major art museums: The Metropolitan Museum of Art and the Smithsonian are both heavily into reproductions now. The National Gallery, during the King Tut exhibit, carried Tut reproductions commissioned by the Metropolitan. Such reproductions have been strongly criticized by those who think they cheapen the originals and, in some cases where not clearly marked, could be mistaken for the originals.

The museum justify the reproductions on the basis that they need the money and that their clearly marked reproductions are an educational service. Rockefeller says few people could afford a Picasso original, but many more could pay $850 for a framed Cibachrome photographic reproduction of Picasso's Jeune Fille a la Mandolin .

The catalogue lends Rockefeller glamor to the objects by photographing them in the Rockefeller residences. His homes include:

Kykuit in Pocantico Hills, N.Y., built in 1893 by John D. Rockefeller Sr. and owned jointly by Nelson and the other Rockefeller brothers.

The modern Japanese house finished in 1974 on the same estate, designed by Junzo Yoshimura and describedby Happy Rockefeller as "our retirement home."

Hawes House, an 18th-century Hudson River Valley Dutch farmhouse, also on the family estate, which was Rockefeller's home as a young bachelor.

The 20-room New York City apartment and the Anchorage at Seal Harbor, both designed by the modern architect Wallace K. Harrison and Jean-Michael Frank, a Parisian interior designer.

With the exception of the New York apartment, the houses have been kept quite private and have seldom been photographed. Now Rockefeller has agreed to stories appearing between now and Christmas on the houses in Connoisseur, House Beautiful, Architectural Digest and Town and Country. The Smithsonian magazine is running excerpts of the book on primitive art.

The most expensive piece in the Rockefeller reproduction catalogue is a $7,500, 411/2-inch-tall, 80-pound statue, copied from a bronze by Auguste Rodin. By the way, the price includes delivery in the continental United States. The cheapest price is $65 each for several different copies of Ch'ien Lung (mid-18th century) Chinese export porcelain piece and a copy of a bronze male sculpture from western Iran, circa 700B.C.

The catalogue has one or two homey notes. "The following three silver pieces are reproductions of Mr. and Mrs. Rockefeller's special favorites for intimate dinner parties." The items are octagonal sterling candlesticks (circa 1717) and a pair of octagonal sterling salt cellar and pepper casters, priced at $475 for the candlestick and $105 and $195 for the salt and pepper pieces. Other catalogues notes are as precise as a museum label.

A great many of the reproductions are China, including copies of the Meissen Swan Service from the early 18th century, a Chinese temple jar ($1,000), a more modestly priced ($300) cobalt blue and gold teapot, as well as a complete matching dinner service. The china was larglely reproduced in Portugla by New york collectors Mildred Mottahedeh and her late husband Rafi Mottahedeh in their Vista Alegre factories.

The only furniture is the exquisite moderne pieces from the New york apartment, designed by artists Alberto and Diego Giacometti with Frank. The coffee table is wood covered with parchment leather-the original was in sharkskin ($2,100). The lamps are a bronze column, gilded with 24-kt gold leaf, topped with a woman's head, and a similar lamp made in a balustrade design (both $1,200). The lamps were lent to the vice president's residence by Rockefeller during his term of office, though he never liked in the house, preferring his Foxhall Road residence.

The reproduction sculpture in the catalogue includes a Degas schoolgirl bronze ($1,000) and a Elie Nadelman bull ($1,100). Their are several African and Mexican pieces. A group of American folk art includes weathervanes and a tramp art box. The paintings and prints include a Toulouse Lautrec and Cezanne (about $325 to $425).

Some of the wood pieces, Murrrow said, are reproduced "by a little woodcaver in upstate New York." The paintings and drawings are Cibachrome, a color photographic process, and framed by Rockfeller's "own framer."

The Sotheby auction lots came from the Washington house, the Seal Harbor cottage and the New York apartment. The objects are not terribly expensive, by Rockefeller standards-about $175 to $10,0000. Of course, even castoffs from a Rockefeller attic can be somewhat above the average.

Some of the Chinese furniture in the sale, notably a pair of 17th/18th century Huang Huali armchairs, may be part of a set originally bought by his mother. He donated several similar pieces from her Chinese furniture collection to the vice president's residence. The chairs are expected to sell for $6,000 to $8,000.

The antique begin at the cheapest with a Sheffield-plated ewer, circa 1790. It's expected to bring somewhere between $175 to $225. The most expensive lot is a Coalport porcelain dinner service, in the deer pattern (circa 1800-10). Guesses are that it will go for $7,000 to $10,000. There are a number of Victorian pieces in the sales: footstools, a four-tier etagere and a huge Victorian dressing chest with inlaid burr walnut ebonized and gift decorated.

The five Rockefeller books with photographs by Boltin will cover modern art. Mexican folk art, architecture and a Rockefeller memoir on his art collecting experiences.