The institution of exploitation of one's unfavorable position and obvious unfairness in Chinese civil law is similar to the windfall profits system the German Civil Code, but they are not identical. Logic problem in relevant legislation and inappropriate system positioning in China may lead to confusions and difficulties in law application. By comparative study, we should re-position the exploitation of one's unfavorable position and obvious unfairness in China Civil by taking advantage of the windfall profits system in German Civil Code in order to solve the problems on legislation and practice through constructing our own Law of windfall profits system.