The invention discloses a cadmium sulfide chemical bath coating reactor. The reactor comprises a base, a vacuum input and output machine, a motor, an underbed, a vacuum glass shell and a heat conducting plate. The underbed is installed on the base, the vacuum input and output machine is disposed on the left side of the base, a temperature gauge is installed on the right side of the motor, the vacuum glass shell is installed on the underbed, and a heater is installed below the underbed. The heat conducting plate is installed above the bottom of the vacuum glass shell, a water drawing and draining pipe is installed on the right side of the vacuum glass shell, a reactor body is installed above the heat conducting plate, and a water circulation impeller is installed on the left side of the heat conducting plate. By means of the cadmium sulfide chemical bath coating reactor, observation is conducted, a complete water circulation system can be accomplished in a closed space, and operation is simple and convenient; moreover, indirect heating of the heat conducting plate is adopted instead of direct heating so that the water temperature can be adjusted more smoothly.