The invention provides a light and temperature regulation type rat tail vein injection instrument and relates to the technical field of mouse experiment devices. The injection instrument comprises a case shell, a base, a cylinder and an insulating substrate, wherein the insulating substrate is laid on the top of the base, the insulating substrate is covered with the case shell, a space partition plate is vertically arranged in the case shell and divides the case shell into an area A and an area B, a bracket of the area A is fixedly connected with a cylinder through a fixing frame, the front end of the cylinder is connected with a spiral vent plug through threads, a clamping groove is formed in a cylinder body at the rear part of the cylinder, a baffle is inserted in the clamping groove, tail holes are formed in the rear end of the cylinder and the lower portion of the baffle, and an electrical component integrated circuit board is installed in the area B; a switch and a liquid crystaldisplay screen are installed on the wall of the case shell, the rear end of the case shell is connected with a tail groove, a temperature control module is installed at the end of the tail groove, a cavity is formed below the tail groove, and an illuminating lamp is installed in the cavity. The light and temperature regulation type rat tail vein injection instrument solves the problems that a white rat is not easy to fix, blood vessels of the tail are not clearly distinguished, the blood vessels are not full, and the success rate of experiment operation is influenced.