Harold L. Peterson, 55, a historian, author, lecturer and chief curator of the National Park Service, died of a liver ailment Sunday at Alexandria Hospital.

He joined the park service in 1947 as a historian, became chief of the historical investigations branch and was named chief curator in 1964.

Mr. Peterson's responsibilites included supervision of professional museum specialists and the acquistion and identification of museum objects for the park service. He also wrote, edited and reviewed historical publications for the service.

He had received numerous awards and honors, including the Interior Departemnt's Distinguished Service Medal in 1958. He also was honored by the park service for his work in reviewing exhibits and audiovisual projects products for the Bicentennial.

Mr. Peterson was active in the Eastern National Park and Monuments Association, for which he served several terms as chairman of the board of directors. The organization assists in the historical, scientific, educational and interpretive programs of the National Park Service.

An authority on antique weapons, armor 18th century military uniforms and flags and historical furnishings. Mr. Peterson had a large collection of arms and armor, and a equally large library relating to the fields in which he was interested. He once said of his collection:

"Armor is more than metal. It's an index of human ingenuity in a pretty basic area - wartime survival.

"Early arms have an intimacy and grace that is lacking in today's mass-produced armaments. Colonial armouers did more than mold protection. They included polish and artistry."

Mr. Peterson served as a consultant to many museums and historic sites maintained by the Army, Navy and Marine Corps. He had been honorary curator of edged weapons at the West Point Museum and associate curator for the U.S. Artillery and Guided Missile Center at Ft. Sill, Okla.

Mr. Peterson also was an adviser on military matters to Colonial Williamsburg and the Plimoth Plantation.

He participated in numerous seminars and workshops sponsored by the National Trust for Historic Preservation, the American Association for State and Local History and the James River Museums Association. He taught at the New York State Historical Association at Cooperstown.

He was the author of hundreds, of magazine articles, and 24 books, which included "The American Sword, 1775-1945." "American Knives" and "The Treasury of the Gun." Editions were printed in many countries abroad.

Mr. Peterson belonged to numerous professional organizations. He was a founder, former president and member of the board of governors of The Company of Military Historians.

He belonged to the American Society of Arms Collectors, the Potomac Arms Collectors and the National Rifle Association, where he held several offices.

Born in Peekskill, N.Y., Mr. Peterson graduated magna cum laude from Drew University and held a master's degree in history from the University of Wisconsin. He served with the U.S. Army in World War II.

He is survived by his wife, Dorothy Parker Peterson, of the home in Arlington: a son, Harold L. Jr., of San Antonio, Tex.; a daughter, Kristin Smalley, of Melrose Park, Ill., and his parents, Dr. and Mrs. Leslie C. Peterson, of Peekskill.

The family suggests that expressions of sympathy may be in the form of contributions to the Eastern National Park and Monument Association in Philadelphia.