The vector control technology of electrically excited synchronous motor is a hotspot in recent years, and the flux linkage observation model is an important part of vector control technology. Reasonable configuration of the flux linkage observation model coefficient is the key to accurately observe the air gap flux linkage information of synchronous motor. A vector control method based on hybrid air gap flux observation model is proposed to solve the problems of sensitive current model to motor parameters and integral initial value deviation. The method not only enables the system to use the current model in the low speed section, but also uses the voltage model in the high and medium speed sections. At the same time, it realizes a smooth transition of the two models so that the whole model is suitable for accurately observing the air gap flux linkage in the full speed range. The MATLAB software and experimental platform are used to simulate and experimentally study the proposed hybrid air gap flux linkage method. The effectiveness of the proposed control method was verified by the results of the simulation and the experiment.