The Senate yesterday approved its second fiscal 1988 appropriations bill, a $10 billion package for the Interior Department and related agencies such as the Forest Service.

The 91-to-5 vote came less than a day after the Reagan administration warned that the president's senior advisers would recommend a veto because the proposal exceeds the administration's target by $1.1 billion.

A similar veto threat has been made against the recently passed fiscal 1988 appropriations measure for the Treasury Department and Postal Service. The White House is opposing subsidized mail rates for nonprofit groups.

Both bills would set spending levels for the year beginning today. This leaves 11 other appropriations bills awaiting Senate action. Meanwhile, the government is continuing to operate under stopgap spending authority.

In other action, the Senate voted, 79 to 19, to approve a bill requiring members of Congress to vote for any future pay raises before they go into effect, preventing the use of parliamentary dodges to avoid such votes.

The pay-raise proviso, intended to bar automatic pay raises for member of Congress unless they expressly vote to approve them, grows out of a controversy last year that resulted in boosting congressional pay from $77,400 to $89,500 a year, when congressional pay raises were linked to automatic pay hikes for senior federal officials.

The Interior bill is $530 million higher than the House's version. The differences will have to be resolved by negotiators from the two chambers.

In another development, the Senate last night confirmed Adm. William J. Crowe Jr. to a second, two-year term as chairman of the Joint Chiefs of Staff, the nation's top military officer.