The work aims to study the trust influencing mechanism in external human-computer interaction (eHMI) to better utilize the potential advantages of eHMI. Firstly, based on the theory of automated trust, six factors influencing trust in eHMI, namely perceived reliability, perceived transparency, perceived familiarity, perceived vehicle performance, perceived brand reputation, and perceived subjective tendency, were proposed, and then the data of 305 respondents were analyzed using the method of structural equation modeling to establish a theoretical model of the factors influencing trust in eHMI. The results showed that the trust formed by pedestrians through the perception of eHMI signals could influence the trust in autonomous vehicles, the trust of pedestrians in eHMI was transferred into the trust of pedestrians in the vehicle to a certain extent, and the auxiliary role of eHMI was reflected. The importance of perceived reliability in eHMI design was emphasized, which could be influenced by familiarity, transparency and brand reputation. Also, pedestrians' subjective tendencies and perceptions of vehicle performance were important factors influencing the level of trust. In conclusion, the findings provide evidence for the importance of trust in eHMI for the future use of autonomous vehicles on the road, as well as providing references and recommendations for eHMI design.