The joint and several liability aggravates the correlation party s responsibility, therefore we should use it discretely.

The validity of the joint and several liability all is united in the positive stimulated effectiveness of behavior whether the law philosophy or the law economy,the premise of which is the information symmetry or the behavior commutation among the behavior entity.

Using the theory of joint and several liability and imputation principle in tort law,three different opinions and cases on whether the party without spilling oil into the sea in two ships collision and only one ship leaked oil should be liable for pollution damage were analyzed.

The paper introduces an case that leads to the main theme,researches the legal effect and liability about unregistered automobile,and demonstrates clearly that the joint liability is against the purpose of legislation and the joint liability is unnecessary.

In our country,the claim pattern of the current joint liability is a free claim pattern.

By using several lemmas and some natures of the convex function and the uniformly convergent function, we prove that the singular points of implicative series are related to the growth of its original series, and obtain some their properties.