The invention discloses a timing synchronization method. The method includes the following steps that a vehicle model built in the TruckSim serves as a first model; a liquid model built in the Fluent serves as a second model; the calculation cycle of the first model serves as a dominant cycle; when timing synchronization occurs between the first model and the second model, data transferring is conducted; when timing synchronization does not occur between the first model and the second model, the second model enters a wait state until timing synchronization occurs; the second model maintains running continuously and is internally provided with a timing sequence discrimination method. The timing sequence discrimination method includes the steps that in the calculation cycle of each second model, when the deviation between the accumulated length of time of the first model and the accumulated length of time of the second model is smaller than or equal to a preset threshold, timing synchronization occurs between the first model and the second model. According to the timing synchronization method, the timing synchronization can be ensured when the two models are combined in use.