A House subcommittee, turning aside budget-cutting requests from the Reagan administration, voted yesterday to allot $201 million in federal funds to the Metro subway system next year to help complete construction of the long-delayed Green Line to Greenbelt.

The action by the transportation subcommittee of the House Appropriations Committee was hailed as a victory by Reps. Frank R. Wolf (R-Va.) and Steny H. Hoyer (D-Md.). The proposed allocation for fiscal 1988 was the same as Metro's allotment this year.

The administration, which failed in an earlier attempt to halt spending for Metro construction, had urged Congress to limit funds for Metro to $130 million next year. The transit authority had sought $250 million.

The House is considered likely to endorse the $201 million spending level for Metro but, congressional aides said, prospects in the Senate are uncertain.

The federal appropriation is designed to help expand the 69.6-mile rail system to 89.5 miles by the early 1990s. Metro officials recently recommended a $2.7 billion plan, including an additional $2.2 billion in federal funds, to extend the system to 103 miles by 2002.

The subcommittee earmarked $500,000 in Metro funds to erect a noise barrier along a section of I-66

The bill would provide $15 million to start repaving and other work along deteriorating sections of the Baltimore-Washington Parkway, $16 million to widen Central Avenue from two lanes to four between Rtes. 202 and 301 in Prince George's County and $4.1 million to continue work on Rte. 1 in Arlington County.

Also included were $9 million to improve railroad signals on a Maryland Rail Commuter Service line between Baltimore and Washington and $250,000 for traffic studies by the Metropolitan Washington Council of Governments.