Senate Majority Leader Robert C. Byrd (D-W.Va.) launched his long-planned effort yesterday to end run Rep. Morris K. Udall (D-Ariz.) and weaken the 1977 strip mine reclamation law.

The law, which seeks to restore land at abandoned strip mines to its original condition instead of leaving it looking like a lunar surface, requires states in developing reclamation plans to follow guidelines spelled out in federal regulations. The coal states, of which Byrd's West Virginia is a leading member, protested that the federal regulations were too burdensome.

Last year the Senate passed a bill which would free the states from following the federal rules. Instead, they would need only comply with the more general language of the statute.

When it reached the House, the bill was referred to the Interior Committee headed by Udall, who was the chief sponsor of the strip mining law and who vowed to do everything possible to prevent it from being chewed up in this fashion. Udall hass succeeded in sitting on the bill and preventing further action since.

Now, Byrd has seized on a minor and noncontroversial House bill which came out of the House Merchant Marine Committee and yesterday offered the strip mine softener as an amendment to it. If he succeeds, the bill could be sent back to the House and approved while Udall sits helpless, unable to get his hands or it.

Ironically, Byrd opened the fight for a provision environmentalists hate just after leading the charge of break a filibuster against the Alaska lands bill, which President Carter has called the environmental issue of the century.

It looks as though Byrd will have to invoke cloture again if he is to get his strip mining amendment passed. Opponents, led by Sens. Howard Metzenbaum (D-Ohio) and John Melcher (D-Mont), have promised a filiguster. Secretary of Interior Cecil D. Andrus sent a letter denouncing Byrd's proposal.

The bill passed the Senate last year by 68 to 26, more than the 60 votes needed for cloture to cut off a filibuster. But since then, several states have solved their problems with the federal regulations and Byrd's strength may have slipped.