About 500 Korean Americans marched from Lafayette Park to the South Korean Embassy yesterday to protest policies of the South Korean government and Reagan administration support for President Chun Doo Hwan.

At a rally and the march to the embassy at 23rd Street and Massachusetts Avenue NW, demonstrators called for an end to what they said was torture of political prisoners; for new presidential elections, and the resumption of debate on a new national constitution that was halted by Chun April 13.

Police said 14 persons were arrested at 7 p.m. for demonstrating within 500 feet of an embassy.

Protesters came from several cities for what organizers called Washington's largest Korean-American march. About 30,000 Korean Americans live in this area.

"Koreans from all walks of life are urging the government to repeal the April 13 measure," said Shin-Bom Lee, director of the Washington-based Commission on U.S.-Asian Relations. "The Korean people have been humiliated by 27 years of military government, which has been propped up by the American government. We want to make the American people know the agony of the Korean people. Fifteen thousand American soldiers died there for democracy, not dictatorship."

The demonstration commemorated a May 1980 incident in which more than 200 civilians were reported killed in the city of Kwangju by the Korean military, said William Hong, president of the Washington-based Korean-American Committee for Democracy and Human Rights, which organized the protest.

It also was to call attention to Chun's decision April 13 to stop negotiations for a new constitution, the recent shake-up of Chun's cabinet and the political and financial scandals that have rocked the South Korean government in recent months. On Tuesday, Chun announced the replacement of eight key government officials after revelations of a police cover-up in the torture death of a student activist in January. The move followed the resignations of all 26 members of Chun's cabinet.

"The regime promised to reform the constitution a year ago," said Kilbyung Soh, chairman of a New York-based Korean-American group. " . . . After a year of empty promises to the people, Chun revealed his true intention and relinquished his promise because he knows too well that his regime will be defeated in any national elections."