The paper aims to study the piezoresistive performance and mechanism of amorphous carbon (a-C) film and apply it in the sensitive circuit of micro-electromechanical system (MEMS) pressure sensor. In this paper, the a-C film piezoresistive material was deposited by direct-current (DC) sputtering process. The phase content and the electrical, mechanical and thermal performance of the representative sample were characterized. Then the device was designed by finite element simulation. And the a-C carbon film pressure sensor was successfully fabricated by MEMS processes to carry out test and analysis of device level. The sensitivity of the pressure sensor chip was 9.4 μV/kPa and the non-linearity of output signal was 5.57% FS (full scale) in the range of 0 to1 MPa. The change of the a-C film resistor’s resistance showed linear relation at –70 to 150 ℃. Especially at –20 to 150 ℃, that relation was stronger, which showed that the temperature compensation for the a-C piezoresistive material was easier in high temperature environment. The phase content varied along the thickness-direction of the film, which implied this direction was also needed to be considered in the mechanism research. In conclusion, the a-C carbon film can be well-combined with the traditional MEMS sensor chip in terms of fabrication process, and mechanical and electrical properties. Finally, the a-C piezoresistive pressure sensor also shows satisfactory sensitivity and linearity Furthermore, the thickness-direction of a-C film should be added into the mechanism research.