Abstract: In order to improve the accurateness of trust evaluation and the applicability of subjective logic, a multinomial subjective logic based extended trust propagation model (MSL-ETPM) was presented, which is composed of trust fusion and trust transitivity. Making the fused opinion more accurate and more in line with the intuitive judgment of human, reputation-based fusion operator of multinomial opinions takes effects of the reputation value and observation circumstance into consideration. Trust transitivity interprets multinomial opinion transitivity as meaning that transitivity process is binomial logical opinion and transitivity information is multinomial opinion, giving trust transitivity formula of multinomial opinion and proving related theorem. Finally, the accuracy and adaptability of the model are put to the proof by example analysis.