Abstract: Antitrust law enforcement system in the United State comprises private enforcement and public enforcement，with the two sectors complementing，checking and balancing each other.The significant role that private antitrust action plays in the United States is quite unique.Since the Sherman Act，private enforcement of antitrust law has been developing in us jurisdiction over a hundred years.Its specific rules and judicial practice is worthy of note.The major functions and objectives of antitrust enforcement are deterrence and remediation in addition to explanation and clarification of the antitrust law and its application standards.Private action has a particular impact on the achievement of these goals.China′s private antitrust enforcement needs further refinement.During the process，special attention should be directed to the experience of the United States，and relevant lessons should be carefully researched.

Key words: American law, monopoly, antitrust law, damage compensation, private enforcement