To investigate the wellbore instability mechanism of coalbed methane (CBM) reservoirs under multi-field coupling effects, a self-developed visualized true triaxial physical simulation test device for surrounding rock deformation of coalbed methane wells was developed. This device primarily consists of a specimen clamping and stress loading mechanism, a temperature loading system, a pore pressure loading system, a drilling simulation system, and a data acquisition system. The features of the device are as follows: 1)It can simulate the geomechanical environment of true triaxial stress, formation temperature, and pore gas pressure in CBM reservoirs. 2)It can simulate the drilling fluid circulation and borehole column pressure by accurately injecting water through the drill pipe and controlling the annular pressure, enabling dynamic monitoring tests of the mechanical behavior of coal rock around the well during the drilling process. 3)It can use a pinhole camera to extend into the wellbore for real-time monitoring of the wellbore deformation and failure process. 4)It integrates sample preparation and testing functions, simplifying the stress loading system, making it comprehensive, lightweight, and straightforward. 5)It allows for parallel monitoring of multiple information such as stress, temperature, pore pressure, local stress, and wellbore deformation visualization around the reservoir well. Using this device, simulation tests of CBM wellbore deformation under varying stress and temperature conditions were conducted. The results show that: the deformation and failure of the wellbore intensify with the increase of the temperature difference between the drilling fluid and the specimen, especially when the specimen temperature is higher than the drilling fluid temperature. The deformation of a wellbore under increasing deviatoric stress evolves through three distinct stages: the initial slow deformation stage, the mid-term rapid deformation stage and the final stable deformation stage. During the mid-term rapid deformation stage, the deformation rate was the most significant.