Currently, with the development of China’s society and economy, traditional marriage value outlook changes obviously, on the one hand, devoice rate is continuously high, on the other hand, husband and wife loyalty agreements increase. In the face of this agreement, some courts pronounce that it is effective but some courts pronounce it is ineffective, the results are paradox and the related people are confused, in addition, in the Explanation III of Marriage Law of People’s Republic of China made by Supreme Court, the change of the attitude to husband and wife loyalty agreement triggers extensive dispute. In perspective of value, husband and wife loyalty agreement not only enhances the implementation of marriage loyalty obligation, maintains the safety of marriage, consolidates the marriage, has no intervention with the marriage but can satisfy the demand of humanity, as a result, the agreement has justification, from the perspective of legal effect, China’s Marriage Law does not prohibit the implementation of will autonomy on disloyal affairs except bigamy and cohabitation and can not deduce that the loyalty of husband and wife should be legally defined, therefore, on the basis of justification, husband and wife loyalty agreement can engage the legal consequence about the disloyal affairs and their real behaviors, whose attribution belongs to general agreement since the agreementmade and in which the engaged compensation for the interest of nonfault party in marriage and compensation sum are necessary restricting method and are not originally objective, thus, laws should regulate it.