Classifying passive appreciation of separate property during marriage constitutes a boundary issue for any statutory matrimonial regime. Basically, there are three different classification approaches, namely the nothing approach, the all approach and the proportional approach. Interestingly, these approaches all coexist and contradict with each other under Chinese family law. This Chapter analyzes them and concludes particularly against the proportional approach which is popular in many jurisdictions, such as in China, the Switzerland and the United States. Further, with an economic analysis (i.e. the revised mimic argument) this Chapter concludes for the all approach that all the passive appreciation of separate property during marriage shall be classified as community property and shared by both spouses equally.