The Interstate Commerce Commission yesterday held the first of a unprecedented number of public hearings to determine the fate of the Southern Crescent, the last privately run, major intercity passenger train in the country.

The Crescent's owner, Southern Railway, wants to discontinue the service.

In all, 23 hearings are scheduled in 21 cities from Washington to New Orleans between now and mid-June. The large number - the most ever held for a single passenger train is warranted by the large number of customers it serves and by the number of protests the ICC has received about its discontinuance.

Last year 165,000 passengers rode the Crescent part or all of the away from Union Station to New Orleans through 30 stations in seven states. "It has become an emotional issue," declared Harold H. Hall, Southern's executive vice president for operations.

Southern, however, thinks of the Crescent in disapassionate economic terms. Its losses on the train for 1977 were $6.6 million, or more than $30 million in the past six and a half years. Scheduled cutbacks or increased promotion would not turn the tide, Hall testified.

While the hearings are to decide whether Southern will be allowed to cut off service on the Crescent, it is politically unthinkable, transportation sources say, that the South would be left without any passaenger train on that route. Accordingly, the Department of Transportation, Southern Railway and the National Association of Railroad Passengers all agree that Amtrak, the government rail passenger agency, should continue to serve the South.

Southern and Amtrak reached tentative accord earlier this year, according to Hall. But then the negotiations were suspended in March. Officially the stumbling block was the new Amtrak board's desire to postpone action and wait for DOT Secretary Brock Adams' study of Amtrak routes, released earlier this week.

Southern claims it could not agree with Amtrak on the value of equipment Southern was to turn over. The National Association of Railroad Passengers says Southern tried to control Amtrak's access to its tracks and the frequency of service so as to keep up the Crescent's high performance standards but at the same time not interfere with Southern's lucrative freight traffic. Whatever the reasons, Southern filed to discontinue the Crescent.

Hearings are scheduled for Charlottesville on May 19, Lynchburg, May 20, and Danville, May 22.