How to choose a suitable kind of buffer operator is very important in practice. Therefore, the characters of traditional kinds of operator and their inherent relationship between regulation degree and smoothness degree are studied. Then, comparative studies on the relationship are conducted among average strengthening buffer operator(ASBO), geometry average strengthening buffer operator(GASBO), weigh average strengthening buffer operator(WASBO), and weigh geometry average strengthening buffer operator(WGASBO). Some theorems about regulation degree and smoothness degree are proposed. Finally, the theoretical analysis and empirical test show the correctness of the theorems.