According to the relation of law to politics, religion and morality, law in the world can be classified in four kinds: professional law, political law, religious law and moral law. Religious law and moral law are subcategory of traditional law, and professional law and political law belong to modem law. It is inevitable that laws of the world will have a confluence and modern law will influence traditional law. The third-world countries and the non-western countries must modernize their laws.