The New York Times announced yesterday that it will test market "a modified edition of the newspaper" in 1,200 homes in the Chicago, Cleveland and Detroit areas for six days, beginning June 18.

The test is expected to be a trial run for a possible national edition of The Times, consisting of two sections - one containing general news and the other business news.

New York Times Co. Executive Vice President Walter E. Mattson, who is general manager of the newspaper, said the project is part of a continuing market research and testing program for The Times, but he gave no specifics.

"We are constantly seeking information that may help reduce distribution costs, improve circulation, and better meet the needs of readers and advertisers," Mattson said.

The papers for the test run will be printed in the New York area and flown to the Midwest, a spokesman for the company said. The Times, over the last year-and-a-half, has reorganized its format and added new feature sections so that it now appears as a four-section paper here on weekdays. Recently, it expanded its business coverage and packages this news in a separate section called "Business Day."

The Time's first edition currently is available in most major U.S. cities on the day of publication, though distribution is limited and the cost can be much higher than the New York news-stand price ifair deliveries are involved.

The Times launched a much-condensed West Coast edition in October 1962, which was printed in Los Angeles, but ended the project in January 1964.