A digital pressure sensor, which is mounted on a pressure controller of a pneumatic tube system, includes a casing including a control circuit, which has a pressure sensing unit, therein, a display, which has a plurality of displaying units for showing numerals or icons, on a front side connected to said control circuit, and a connection tube on a bottom thereof for communication with a connection tube of the pneumatic tube system that said pressure sensing unit of said control circuit senses a pressure in the tube via said connection tube; and a battery set received in said casing and electrically connected to said control circuit.