Abstract: As a result of one-sided emphasis on the guarantee of custodial coercive measures and neglect of the humane care and protection of human rights,although custodial measures used in the cases have played a good role,the effect has not been handling in proportion.The confused awareness of the nature of custodial measures is an important cause.In this paper,I expound its nature on the aspects of its evil,good,humanism,modest restraint,purpose,obligations and the Nash equilibrium to broaden our horizons.And it also gives theoretical support to rediscover and construct the custodial measures.