The House voted 385-23 Thursday to order President Reagan to use U.S. military might to stop the flow of illegal drugs into the United States.

The vote approved a proposal backed by conservative Republicans to tell Reagan to "deploy equipment and personnel of the Armed Forces sufficient to halt the unlawful penetration of United States borders by aircraft and vessels carrying narcotics."But the measure is a long way from becoming law. Even Rep. Jack Davis, R-Ill., one of its strongest supporters, admitted, "Yes, it is flawed."

The proposal was added as an amendment to a Pentagon budget bill. The final provisions of the huge bill will be worked out later this year by a House-Senate conference committee after the Senate approves its version of the bill.

In two previous years, 1985 and 1986, the House also voted to use the military to help stop drug trafficking, but those provisions were knocked out by the conference committee. They were strongly opposed by the Pentagon.