Abstract: Self-deception has always been the focus of research in psychology. However, after decades of research, the complete cognitive processing of self-deception is still unclear. By comparing the results of previous studies of the preconditions, internal processing and the states after self-deception, a mental processing model of self-deception was constructed: driven by the motivation of self-deception and masked by cognitive ambiguity, individuals can process relevant information with bias; in the simple processing stage, where information is searched for and perceived, undesirable data may be rejected; in the deep processing stage, where information is evaluated, understood and stored, more mental resources will be allocated to desirable information; because of these processing biases, unwelcome information cannot be duly processed, which leads to a slow change of individuals from the positive belief supported by unpleasant message to the negative belief supported by desirable message; finally, depending on the proportion of evidence supporting positive and negative beliefs respectively, individuals form a state of unconscious self-deception or conscious self-deception. This complete mental processing model can help researchers see the whole picture of cognitive processing of self-deception and provide reference for researchers to better study self-deception. Moreover, the new model can expand the scope of this research field and guide the researchers to study the deep processing mechanism of self-deception.