Aggregate signature can aggregate different signatures on different messages from different signers into one single signature and require to be verified only once, this enables batch verification of message signatures. Certificate-based cryptosystems not only can simplify the certificate management in traditional public key cryptosystem, but also overcome the inherent key escrow in identity-based cryptosystem and eliminate lower credibility of trusted third-party in certificateless cryptosystem. Based on the advantages of aggregate signature and certificate-based cryptosystem, this paper proposes a secure certificate-based aggregate signature scheme by using bilinear pairing. Under the computational Diffie-Hellman assumption, it is proven secure. Compared with the previous certificateless aggregate signature scheme, our scheme does not need a secure channel, which is more suitable for the application prospects of wireless sensor networks.