The invention provides a hybrid power system, which integrates an internal combustion engine with a solid oxide fuel cell (SOFC) stack and provides power for the vehicle through the internal combustion engine at first in the preheating stage of the SOFC stack, thereby solving the problem that an SOFC stack is unable to provide power for the vehicle in the preheating stage. At the same time, the internal combustion engine burns fuel gas, outputs high temperature exhaust gas, heats the heat exchanger with the high temperature exhaust gas, then discharges the exhaust gas from an exhaust turbine and inhales air from the outside of the system. The air first passes through an air preheater, then passes through a heat exchanger and then enters the inside of the SOFC stack, preheats the air preheater through an air pipeline and then is discharged. After multiple cycles, the preheating of the SOFC stack is completed. As the air preheater is connected to the heat exchanger in series to heat the air, the heating speed of the air entering the SOFC stack is raised, the preheating time is shortened and a quick start of the SOFC stack is achieved so that the SOFC stack can be used to achieve the purpose of providing power for the vehicle efficiently.