A pressure sensor has a housing, an air lead-in hole, a pressure lead-in hole, an inner cavity, a sensor chip, a lead frame and a cover plate. One end of the air lead-in hole is in communication with the inner cavity of the housing, and the other end of the air lead-in hole is in communication with the air; the pressure lead-in hole is perpendicularly disposed at the center of the upper surface of the housing, two steps are disposed on the upper surface of the inner cavity, and a horizontal surface-mounted device surface is disposed on each of the steps. The center of the sensor chip is aligned with the centers of the pressure lead-in hole, and the lower end of the pressure lead-in holes are in communication with the cavity of the sensor chip.