Abstract: The aim of this study was to examine the changes of the synovial tissue in rabbit temporomandibular joint (TMJ) internal derangement (ID) models using light and electron microscope. Thirteen rabbits were included in our study. The right TMJ of all animals were used as the experimental group while the left ones as the control group. ID model was established by using elastic rubber rope to stretch anteriorly. Synovial tissues were collected and examined by light and electron microscope to observe microstructure and ultrastructure changes after establishing the model. CD34 was used to count small blood vessels. A paired t test was performed with SPSS 16.0 software package to compare the data of the experimental and the control side. The average number of small blood vessels in the experimental side was significantly greater than the control side both in the first and second week. Numerous synovial cells of type A and type B were detected under electron microscope, and type A cells shrunk after a period of time. This study is helpful to understand the development of the TMJ intra-articular adhesion.