MEMS capacitive sensor with automatic range

The invention discloses an MEMS capacitive sensor with an automatic range, which comprises an MEMS capacitance sensitivity module, a capacitance/voltage conversion module, an A/D module and a microprocessor, wherein the MEMS capacitance sensitivity module is a capacitor formed by a sensitivity movable structure and a fixed structure; the sensitivity movable structure sensitively detects mechanical deformation generated by a to-be-measured physical quantity; the capacitance/voltage conversion module converts the capacitance change quantity into a voltage signal; and the A/D module samples the voltage signal and outputs the voltage signal to the microprocessor. Through adjusting a DC bias voltage difference at two ends of the capacitor, the magnification times of a sensitive element can be adjusted, and the range of the sensor can be adjusted to a set range. The detection range of the MEMS capacitive sensor can be expanded, and especially for a weak to-be-measured quantity, the signal-to-noise ratio of the sensor can be improved, and the weak signal detection precision is increased.