The fuel injection ring is an important part of the micro-turbojet engine. The uniformity of fuel injection quantity determines the uniformity of the temperature field in the combustion chamber. Aiming at micro-turbojet injection ring uneven fuel injection problems, the influence of pressure loss is compensated through the use of unequal-diameter needle structure. By using CFX software, the experiment of three-dimensional flow field inside the fuel injection ring is simulated and the outlet flow rate, outlet velocity and the pressure change of the entire internal flow field of injection needle on the injection ring body are calculated and compared with the experimental results. Results show that the scheme of unequal injection nozzle can improve the problem of nonuniform injection of fuel injection ring. According to the calculated results, we can lay the foundation for the study of the internal flow field of the injection ring.