The invention belongs to the technical field of sensors, in particular to a resonator based on electrostatic driving and differential piezoresistance detection and a pressure sensor thereof. The pressure sensor comprises a cover cap, a resonator, a pressure sensing structure and a base, the cover cap, the resonator and the pressure sensing structure are rigidly connected through bonding to form avacuum cavity, and an electrostatic driving electrode, a first mass block, a second mass block, a resonance beam, a piezoresistive strip and a first connecting block are located in the vacuum cavity;and the base is in rigid connection with the pressure sensing structure through bonding and is not in contact with the pressure sensing film. An in-plane dynamic balance resonance mode of the annularresonance beam is adopted, the Q value of the sensor is increased, and the thermal elastic loss is reduced; and the working mode of electrostatic driving / differential piezoresistance detection is adopted, the output signal strength of the sensor is improved, the temperature of the resonator can be represented in situ, and the pressure measurement precision is improved through temperature compensation of the sensor.