With social transformation,social strata disunite increasingly, benefit groups become more complicated, profession prestige deviates from income and the gap between the poor and the rich enlarges. As a result,social tension strengthens. The defect of institution design and the flaw of institution execution block the way from settling social tenseness, which results in increasing crime rate. The anthor points out that criminal phenomena come from the social tenseness, which is not settled, in social disunion.