The Computation method of Solid Ducted Rocket (SDR) is a complex problem. It needs to effectively solve the two mixing and combustion processes, and is also affected by many factors such as the overall scheme and propellant type. In order to find a suitable method, physical model, simplified hypothesis, control equation, turbulence model, combustion model, etc. were investigated. Subsequently, calculations were carried out based on the Vanka model, and finally the results of pressure, temperature and combustion efficiency were obtained. The results show that the proposed method is practicable, and the accuracy and efficiency are ideal. Combustion efficiency is only 77.4%, and the Vanka model must be further improved by the air and gas intake modes. The results can provide reference for relevant research.