As for the laboratory fuel consumption measurement system, a program design was conducted, AMESim software was used for the simulation analysis about the system. The relationship curves of the valve body position and hotcold water temperature with the system outlet temperature were acquired by batch function of the software, and the mass flow measurement accuracy of the system with different line pressure was analyzed. The results show that the outlet temperature of the system changes from the minimum to the maximum linear with the changes of the temperature of the hot and cold water, outlet temperature of the system can be precise controlled by adjusting the position of the valve body, and the changes of line pressure will cause fuel short back, but will not affect the precision of the system. The research provides reference for building and improvement of fuel consumption measurement system.