The certificate-based encryption schemes often limit the message space to a particular group and are not adaptive to encrypt large messages. In order to solve this problem, the study extends the concept of key encapsulation mechanism with tags to the certificate-based encryption, and then proposes the notion and security model of the certificate-based key encapsulation mechanism with tags (CB-TKEM). In addition, the paper presents a construction of CB-TKEM that is provably secure against IND-CCA2 in the random oracle model.