President Reagan's record-high peacetime defense budget cleared its first congressional hurdle with ease yesterday as the Senate Armed Services Committee authorized practically all the money he requested for weaponry: $136.4 billion.

Funds for other activities -- paying soldiers, constructing airfields -- will be handled in separate legislation to push the total for defense up near the full $222 billion requested for fiscal 1982.

Chairman John G. Tower (R-Tex.) acknowledged that he rushed the bill through committee in hopes of staving off cuts that he feels senators will try to make later in the year in lieu of reducing domestic programs to the level of Reagan administration is advocating.

In looking beyond the current year at military manning problems, such as finding enough skilled sailors to run all the new ships being ordered, Tower said that it is his "personal view" that "ultimately we're going to have to go back to Selective Service" -- meaning draft calls.

Because some people are joining the military for lack of jobs in the civilian marketplace, Tower said that the faster Reagan manages to improve the economy, the quicker the services will have to resort to the draft to fill their ranks.

All told, the committee cut only $11.1 million from the total that Reagan requested for ships, tanks, planes and other weaponry. But it redistributed millions among the Pentagon's various accounts.

Losing out in this shuffle were the Army's Patriot anti-aircraft missile, which has encountered technical problems; the Navy's 10th Trident missile submarine, because of construction foul-ups at Electric Boat shipyard, and the Air Force's CX cargo plane.

As was the case last year, Tower said the Air Force could not satisfy the committee that it had a clear idea of what kind of plane it would build under the CX program. The chairman said there was a crucial need for such planes to airlift gear to distant trouble spots like the Persian Gulf, but that the CX did not seem to fit the bill as yet.

Chief beneficiaries as the committee redistributed money among the Pentagon's accounts were the Army National Guard and the Navy Reserve. The Guard was authorized to buy 12 A7K figther-bombers and 12 C130H transport planes which the administration did not request. The Navy Reserve, under the committee bill, would get 12 C9 transports and two P3C anti-submarine planes.

The committee approved most of the big-ticket items in Reagan's defense budget, including:

$2.45 billion for the MX land missile, with the proviso that the money not be spent until the administration tells Congress how the weapon will be deployed.

The MX is engulfed in controversy. Sens. Jake Garn (R-Utah) and Paul Laxalt (R-Nev.) said again yesterday that they opposed the Air Force plan to deploy the MX on the valley floors of their home states. A better idea, they maintained, would be to put the MX missile in existing Minuteman silos in the northwest and protect the missiles with a new anti-ballistic missile system.

$2.2 billion to build a new bomber. Tower said that "the sense" of his committee is that the new bomber will be an undated version of the B1 that President Carter canceled in 1977. Defense Secretary Caspar W. Weinberger is nearing a decision on what bomber to recommend to President Reagan for the 1980s and 1990s.

$2 billion for 120 Air Force F16 fighter-bombers.

$1.98 billion for 58 Navy F18 fighters.

$1 billion for 720 Army XMI tanks.

The committee gave its blessing and the first down payment for bringing the battleship New Jersey out of mothballs but refused to go along with reactivating the aircraft carrier Oriskany on grounds the cost estimates were unreliable and the mission dubious.