Abstract: The Double-Heat mass flow sensor has the characteristics of high accuracy，quick response and good adaptability to the temperature for the micro gas flow measurement.This paper uses ANSYS.FLUENT software，starting from two evaluation index which reflects the sensor performance，linearity and sensitivity.Numerical simulation analysis by changing the heat flow，heat distance，diameter of tube.The main factors affecting the performance of Double-Heat Mass Flow Sensor，which can provide the basis for improving the quality of Double-Heat Mass Flow Sensor，are concluded.