Abstract: This paper proposes a method combining design error types with assertion classification.This method is based on common RTL errors to guide the assertion selection in different classification aiming to enhance the pertinence and purpose of inserting assertion.Furthermore,this paper also proposes the hierarchical assertion design method splitting the complex assertion design into multiple hierarchical steps to decrease the difficulty of assertion design and to reduce the errors of assertion codes.Verification examples show that the proposed methods can achieve efficient assertion insertion and improve the efficiency of function verification significantly.