The design and manufacture method of a silicon mass flow sensor made with silicon micromachining (a.k.a. MEMS, Micro Electro Mechanical Systems) process for applications of gas flow measurement with highly humidified or liquid vapors is disclosed in the present invention. The said silicon mass flow sensor operates with an embedded heater and an adjacent control temperature sensor beneath the integrated calorimetric and thermal dissipative sensing thermistors. When the condensation takes place at the surface of the said silicon mass flow sensor, the embedded heater shall be turned on to elevate the temperature of the supporting membrane or substrate for the sensing thermistors. The elevated temperature shall be adjusted to above the vaporization temperature with the feedback data of the adjacent temperature sensor such that the surface condensation due to the presence of the liquid vapors in a gas flow can be effectively eliminated.