Based on the existence of issue crossing, the international law and mechanism about coping with climate change and promoting free trade facing the problem of Systematic coordination. Through cross disciplinary research of international law and international relations, the interaction for climate and trade international mechanism has the theoretical basis. At present, carbon trading mechanism, unilateral carbon reduction measures, technology transfer mechanisms; issue crossing in international law between climate and trade; and then propose solutions for the systematic coordination from the perspective of international law and mechanism. China should play a positive role in this process.