Law is so closely interrelated with society that when taken apart from its social arena, people fail to imagine what it is. On the contrary, society, without law, not only fails to be maintained but also fails to exist. Therefore, what is the function of law? How to study law so as to make function better? These become important subjects as far as modern jursprudence is concered.Legal sociology is a part both in jurisprudence and in sociology. It treats law as a social norm and also as a social pheromenon. It can satisfactorily meet the practical needs to observe the functioning of law and its research method by means of legal sociology, for by the said approach, people can clearly examine the functioning of law and its research method and hence solve the problem arising from the disaccord between sein and sollen.