Abstract: By analyzing the security of strongly secure certificateless signature scheme proposed by Wang Yafei et al, the problem that the scheme could not resist public key replacement attack under dishonest KGC was pointed out. Aiming at this problem, the behavior of KGC was restrained by the change of traditional certificateless algorithm sequence KGC bulletin board where user public key make public, and verifiability of facticity of public key through the local private keys and public keys. The analysis of security shows that the improved scheme cannot only resist the public key replacement attack based on dishonest KGC, but also be more efficient than the existing schemes for avoiding pairings and inverse operation.