The invention provides a dynamic lightweight class trust evaluation method based on the Bayesian theory and the entropy theory, and belongs to the technical field of wireless sensor network security. The dynamic lightweight class trust evaluation method based on the Bayesian theory and the entropy theory includes the following steps: S1, an evaluation subject calculates the direct trust value of an evaluation object according to the Bayesian theory; S2, the evaluation subject updates the direct trust value of the evaluation object by means of attenuation factors and valid history memory periodically; S3, the evaluation subject calculates the confidence coefficient of the direct trust value of the evaluation object, and judges whether the confidence coefficient is larger than a certain threshold value to determine whether the indirect trust value of the evaluation object needs to be calculated or not; S4, the evaluation subject confirms the bang path of the recommendation trust values, confirms the weight of the recommendation trust values by means of the entropy theory, calculates the indirect trust value of the evaluation object, and calculates the comprehensive trust value of the evaluation object through the combination of the direct trust value and the indirect trust value of the evaluation object. The dynamic lightweight class trust evaluation method based on the Bayesian theory and the entropy theory is in accordance with the characteristics that sources such as capacity, calculation, and storage of network nodes are limited and has the advantages of being dynamic, adaptive, lightweight and the like.