Signcryption is a cryptography primitive which can provide message confidentiality and sender authentication in a single logic step. In order to improve computational efficiency of certificateless aggregate signcryption scheme based on bilinear pairings, a new CertificateLess Aggregate SignCryption (CLASC) scheme based on bilinear pairings was proposed. In the proposed scheme, any user could be allowed to be an aggregator to initiate the signcryption protocol. After signcryption ciphertexts were generated by users, the ciphertexts were sent to the aggregator for aggregating to be one single ciphertext. The scheme was proved to be existentially unforgeable and confidential under the random oracle model through security analysis. The comparison results show that the proposed scheme only requires pairings operation only once for each signcryption user, which can improve the computational efficiency and can be applied to applications with high real-time requirements.