With the functioning conditions and their influence on the effect of the contracts, the thesis mainly discusses the application of legal right of cancellation, licensed right of cancellation and right of termination of performance of a contract to a contract which can not be cancelled with free will.

There are various occurrences in the civil law of the right of revocation,that is of private law in nature, and there are not enough discussions on the nature of it in general although discussions on its various aspects are many.

It is recognized that although real estate dual sales are not inhibited by law, the creditor (prior purchaser) could, under certain conditions, enforce the right of revocation.

Providing the act with defect in meaning expression obtains full effect,it is contrary to the autonomy of the parties,therefore,such act always does not have full validity in the civil law of many countries and it produces some relative rules,one of which is the exercise of right of rescission.

3 The creditor of the person who abandoned the right of succession cann t regard the acts as the subject-matter of the right of rescission.

The right of rescission is the expansive creditor s right.

The tax revocation is a new system in our tax laws, but few people observe its nature in our country,there is no clear prescription in the contract laws and the tax laws of China about the nature of the right of evocation.

There is quite different for tax authorities to practice subrogation and revocation in the nature, method and procedure from the original civil subject.