The performance of ignition directly affects the success of in situ combustion. Because of the low temperature and heat loss in the formation, it takes a longer time to ignite and the success rate of ignition is relatively low. The steam injection preheating can shorten the ignition time and reduce the ignition cost greatly. However, thus far, there is relatively no complete design method for steam injection. On the basis of the heat conduction equation of formation, the paper evaluates the effect of the preheating process by laboratory experiments and derives a mathematical equation of temperature distribution of steam injection preheating. In addition, considering the ignition threshold value and oxidation characteristics of crude oil, the paper also designs preheating parameters of steam injection. With the mathematical equation and preheating parameters, the performance of ignition can be optimized to establish table combustion rapidly. Finally, on the basis of the field data, the paper presents a practical calculation case. The results and findings suggest that more amount of steam injection does not necessarily lead to better performance, and a recommended value of the amount of stream injection is given.