私法自治强调的是当事人以自己的意思发生私法上的权利和义务关系,所以法律行为就是实现私法自治的最佳手段。作为法律行为核心要素的意思表示的完整、无瑕疵,便成为私法自治的重要因素。但是,法律如何在意思自治和交易安全的矛盾中做出价值判断和选择,就显得尤为重要。性质错误作为一种特殊的动机错误,在法律的价值判断中起着至关重要的作用。 The emphasis of private law autonomy is that the parties, in their own right, have the rights and obligations of private law. Therefore, legal acts are the best way to realize the autonomy of private law. The completeness and flawlessness of the meanings of the core elements of legal acts have become an important factor in the autonomy of private law. However, how the law makes value judgments and choices in the contradiction between autonomy of autonomy and transaction security is particularly important. As a special kind of motivation error, the nature error plays a crucial role in judging the value of law.