The court of U.S. traditionally take a cautious attitude towards whether social legislation violate the right to equality and respect for the judgment of legislators to avoid giving substantive intervention. However, with the improvement of consciousness of the social public in welfare rights, the US court take some measures gradually, such as strengthening the standard of judicial review to the reasonableness of social legislation content, examining reasonable correlation between the legal ends and legal means, requiring substantial reason of the differential treatment, restricting the discretion of the legislative, in order to achieve the equal protection of the social legislation.