Abstract： Objective To evaluate the effect of root canal taper and post on tooth stress distribution. Methods Three-dimensional finite element models of human mandibular first molar with root canals prepared with 35# K file, ProTaper and Profile were established. The tooth were restored with fiberresin, stainless steel and silver amalgam posts respectively. A vertical load on tooth occlusal surface was simulated. Marc software was used to analyze and calculate the stress distributions in the tooth restored with three kinds of different root canal posts, especially the in the cervical part and root. Results Different tapered root canals had no obvious influence on stress distribution in all three different posts. Stress distribution of stainless steel post located at the cervical and middle part of distal root, the highest Von-Mises stress was about 45 MPa. Stress distribution of silver amalgam post located at the orifice of root canal and pulp fundus, the highest Von-Mises stress was about 16 MPa. Stress distribution of fiber-resin post had no obvious stress concentration. Conclusions Fiber-resin post is the most ideal root canal post. Stainless steel post causes remarkable stress concentration in the root, which may raise the possibility of root fracture.