Abstract: The spirit of expectant possibility is that "Law can't force people". This is not only used in common law. Chinese Criminal Law adheres to and embodies this value idea. If we want to explain the expression and systematic status of expectant possibility in Chinese Criminal Law, we need to choose and introduce foreign theories. Expectant possibility is an evaluation system out of crime, and it's out of the legal causes. The expression and systematic status of expectant possibility in Chinese Criminal Law can't be explained in system of constitution of crime. The proviso of article 13 in Chinese Criminal Law says "The plot is significant slight and has little harm", this contains the expression of expectant possibility. Expectant possibility is a part in criminal theory, which is parallel to the system of constitution of crime.