Cryptographic workflow is a special cryptography system working model in multi-user situations, in which a message is encrypted according to some policy so that only entities guided by the policy are able to decrpt the message. To realize the unforgeability of key encapsulation in without escrow cryptographic workflow, a new key encapsulation mechanism supporting cryptographic workflow based on signcryption is defined. Firstly, a generic model of key encapsulation supporting cryptographic workflow is defined. The corresponding security model of the generic model is also given. Following the generic model, a construction scheme for key encapsulation mechanism supporting cryptographic workflow is proposed by combining secret sharing scheme, ID-based encryption scheme and signcryption scheme. The security of the proposed scheme is proved in standard model with sequences of game. The proposed scheme can satisfy the receiver security and the external security characters in cryptographic work.