CONTROL and compassion should be the twin objectives of American immigration policy, and legislation recently introduced by Sen. Alan Simpson (R-Wyo.) and Rep. Romano Mazzoli (D-Ky.) has these two goals in mind. Any bill that has the bipartisan cosponsorship of the House and Senate chairmen of the immigration subcommittees is off to a good start. This one deserves to be.

About 800,000 immigrants entered the United States legally in 1980. Some came as refugees; some came under country-by-country quotas; others came as close relatives of Americans and were admitted without reference to quotas. In addition, however, it is estimated that about 500,000 migrants enter the country illegally each year, joining a growing number of undocumented persons -- more than 6 million -- who are already here. It is this flow of illegal immigrants that concerns law enforcement officials, labor unions and just plain citizens who fear that we have lost control of our borders.

The solution proposed by the Simpson-Mazzoli bill is to diminish the incentive for undocumented workers to come here by penalizing employers who hire them. Effective enforcement of this law would require job applicants to present proof of employ-ability and legal immigrant status. For the first three years, documents such as a Social Security card, birth certificate, passport or driver's License would be enough. Eventually a nonforgeable, permanent and universally accepted card would be used. This provision is opposed by some Hispanic organizations that fear discrimination. The law, however, is designed to penalize only those lowwage employers who choose undocumented workers over American citizens and legal immigrants, many of whom are themselves Hispanic.

The bill is also compassionate in a number of respects. It would set the number of legal nonrefugee immigrants allowed into the country at 425,000 a year and maintain preferences for families of American citizens and permanent residents.

While no country may send more than 20,000 immigrants, special provision is made for Canada and Mexico. Each of these neighbors would have a quota of 40,000, and either country would be entitled to the unused visas of the other from the previous year. The bill would continue the present law permitting the president and Congress to adjust the number of refugees admitted on a yearly basis, an approach meant to deal with international emergencies, and it would allow a generous amnesty for those who entered the country illegally but have been settled here since before 1978.

This legislation is the product of many months of committee hearings. It reflects, in some measure, the recommendations of the Select Commission on Immigration and Refugee Policy -- an advisory group created by Congress to propose reform of the immigration law -- and is an improvement on the administration's less comprehensive bill. Sen. Kennedy, the senior Democrat on the Judiciary Committee, characterized his Wyoming colleague's proposal as an "extraordingarily important bill, bridging many of the conflicts and controversies that exist in this area." The country needs an overhaul of the immigation law that reflects its better values and most pressing obligations. This is it.