David Truong, the Vietnamese expatriate convicted of spying for Communist Vietnam, was freed on $250,000 bond yesterday after Supreme Court Justice William J. Brennan Jr. ordered bail reinstated and reversed lower court ruling.

Brennan, in a four-page opinion, rejected contentions by U.S. District Court Judge Albert V. Bryan Jr. and the 4th U.S. Circuit Court of Appeals that Truong was likely to flee if released on bail.

The appeals court maintained in an unpublished opinion that Truong has remained in contact with the Vietnamese ambassador in Paris, has not established a permanent residence in the United States and that if he should flee the government would have no way legally to retrieve him.

"...If these considerations suggest opportunities for flight, they hardly establish any inclination on the part of (Truong) to flee." Brennan wrote. "And other evidence supports the inference that he is not so inclined."

Brennan cited the fact that when Truong was released on the same bond pending his trial in May he appeared in court and "affirmed at sentencing his faith in his eventual vindication and his intention not to flee if released on bail." Brennan also said that Truong has continuously lived in the United States since 1965 and has no community ties.

At a hastily called hearing yesterday afternoon to determine the terms of Truong's release, Bryan ordered Truong personally to appear every day before either a U.S. marshal in the District of Columbia or Alexandria. Truong also is barred from leaving the Washington metropolitan area without Bryan's permission.

The Alexandria U.S. attorney's office, had recommended that Truong be required merely to telephone the marshal.

"I feel that's excessive," Truong said outside the courtroom about Bryan's ruling. "Although I'm on bond, it's virtually house arrest."

Truong said he had hoped to get a job while on bond, but said it will be difficult since he will have to report to a marshal every day. He added he will try to give speeches around the country saying that his case is a political one.

Lawyers for Truong, who was sentenced to 15 years in prison for various espionage and conspiracy charges, appealed to the Supreme Court for bail last month. They noted that their appeal of the entire case was based on their challenge to the admission of evidence obtained from a warrantless surveillance personally approved by President Carter and Attorney General Griffin B. Bell.

Truong's codefendant, former U.S. Information Agency employe Ronald L. Humphrey, had never been able to pay his $150,000 bond and that was revoked at his sentencing. His lawyers have not appealed his bail but said yesterday they are thinking of doing so in light of Brennan's decision. Humphrey, who was also sentenced to serve 15 years, is in the Alexandria jail.

Truong had raised his bail through charities and collateral on his sister's home in Los Angeles.