The New York Daily News, which struggled for a year to crack the afternoon market here in an attempt to boost flagging circulation, today threw in the towel and said it would close its Daily News Tonight edition.

Robert M. Hunt, publisher of the nation's largest-circulation general newspaper, said the Daily News would lay off 320 of its 4,100 employes, freeze some salaries and cut executive pay 10 percent to try to cut losses at the tabloid.

Even with the cost-cutting measures announced today, the Daily News will lose $11 million this year, Hunt told reporters.

A spokesman for 11 of the morning newspaper's unions said workers understood why the afternoon paper was folding. George McDonald, president of the Allied Printing Trades Council, said unions were willing to cooperate with News management but want to be able to check the company's books and participate in management decisions.

Hunt called the union's proposals a "thoughtful initiative" and said the News would have a response to their requests on Wednesday.

"We don't want a Washington Star situation," McDonald said. The Washington Star closed Aug. 7, as have many afternoon newspapers in major metropolitan markets. The Philadelphia Bulletin has said it will close on Sunday unless it gets concessions from its unions. Both afternoon dailies in Chicago -- Today and The Daily News -- folded in recent years.

Chicago Today was owned by the Tribune Co., which also publishes The Chicago Tribune and The New York Daily News.

The Daily News sunk $20 million into Tonight, trying to produce a product aimed at the "upscale" Manhattan and suburban reader who reads The New York Times and The Wall Street Journal in the morning. When Tonight was launched a year ago, the News had high hopes.

It hired a separate staff for the afternoon edition, under the editorial direction of Clay Felker, who fashioned both the Village Voice and New York magazine, which has become the prototype for city magazines across the country.

But the long features, analysis and increased business coverage did not attract the "new audience of readers and advertisers" the News hoped they would. Instead, readers either opted for the racier New York Post, an afternoon tabloid, or no newspaper at all. The prestige advertisers, such as Bloomingdale's and Brooks Brothers, ran occasional ads but concentrated their budgets on the morning New York Times.

"We gave it our best shot," Hunt said. "We went out to produce the liveliest, most interesting editorial package we could and, damn it, it didn't work. The market isn't there."

Hunt attributed the demise of Tonight to a bad marketing decision on the part of the News and to the general decline of afternoon newspapers throughout the country because of television news.

Tonight's circulation apparently never reached more than 115,000 a day and now is selling about 70,000 copies. Overall Daily News circulation is just under 11/2 million, with more than 1.3 million of those papers distributed in New York City and the nearby suburbs.

Despite the addition of Tonight, Daily News circulation tumbled 63,000 during the last year. At the same time, The New York Post, which launched a morning edition just before the News invaded the afternoon field, gained 78,000 circulation to 732,000 a day.

Sources said that the morning edition of The New York Post accounts for nearly half its daily circulation, but Post circulation director Martin Fischbein would say no more than that the paper's year-old venture into the morning field is "important" in terms of circulation.

The presses begin to run at 10 p.m. for the Post's first edition and continue until 4:50 p.m. the following day.

The Daily News Tonight replaced the morning paper's so-called "Night Owl" edition that hit the streets about 8 p.m. Hunt said that the News will not revive the Night Owl, which sold about 80,000 copies. The News will start its presses at midnight.