The National Gay Rights Task Force yesterday called on the government to stop treating homosexuals as security risks and said a 30-year-old presidential order restricting employment of gays should be stricken from the books.

The group also said it plans to survey presidential candidates about issues affecting gay men and lesbians.

The executive order, issued by President Eisenhower during the McCarthy era, has since been modified to apply only to sensitive government positions. Yet in the 30 years it has existed, the group said, there has been no evidence of foreign agents obtaining national security information by threatening to expose an employe's homosexuality.

But government policy "still assumes that the gay or lesbian employe is more likely to be blackmailed than his or her heterosexual counterpart," said Virginia M. Apuzzo, the group's executive director. "It remains a source of harassment and a barrier to truly equal employment opportunity for gays and lesbians in the federal government."

Apuzzo complained that prospective government employes who are homosexual are subjected to a "degrading line of inquiry" about their sex lives that is not required of heterosexual job applicants.

In the majority of cases, the group said, gays can obtain government employment. But at the CIA, FBI, the National Security Agency, the Foreign Service and the military, where security clearances are required, policies discriminating against homosexuals are still in effect.

John D'Emilio, who authored a study of federal policies affecting gays, said 655 homosexuals were dismissed in the first 16 months of Eisenhower's national security program. At the State Department during 1954-55, he said, two employes were fired because of Communist Party membership and 104 employes were fired on charges of "sexual perversion."

He estimated that "tens of thousands" more homosexuals were subjected to civilian and military surveillance and harassed by local law enforcement officers in the wake the federal campaign against gays.

Franklin E. Kameny, a task force founder who was fired in the 1950s from his government job because he is homosexual, said yesterday that federal employment policies, now being reviewed by the Reagan administration, will be challenged in court if they do not provide fair treatment for homosexuals.

"We've been willing in the past to indulge the government that there is at least some validity in the blackmail charge," Kameny said. "Now we're taking a much harder line."