Objective To design a occluder suitable for the anal fistula internal mouth occlusion surgery, study structural design of the occluder, as well as the interaction between implants and tissues, and evaluate performance of the internal mouth occlusion. Methods The overall structure of the occluder was designed and the prototype was manufactured. The finite element model of occluding was established to study the stress distribution and damage area of tissues during occlusion; the tissues puncture experimental platform was built to verify the simulation model and results; the pull-out force test platform was built to evaluate the occlusion effect of the internal mouth. Results During the occlusion process, the maximum torque of the feeding mechanism was 36 mN · m, the maximum stress of the tissues was 19.75 MPa, and the damage area was 1.35 cm2. The finite element model was basically consistent with the experimental results, and the maximum pull-out force reached 5.11N. Conclusions The area of tissues damage in the process of occlusion meets the requirements of minimally invasive treatment of anal fistula. The minimally invasive anal fistula occluder designed in this study can effectively occlude the internal mouth, which is helpful for doctors to perform minimally invasive surgery for anal fistula more conveniently, quickly and effectively.