The invention discloses a numerical control pneumatic engine, which comprises an energy supply system, an energy conversion system and a control system. The energy supply system consists of a high-pressure air storage tank, a manual valve, a control electromagnetic valve A, a primary heat exchanger, a primary decompression cylinder, a control electromagnetic valve B, a secondary heat exchanger, a secondary decompression cylinder, a control electromagnetic valve C, a quantitative pre-spraying cylinder and a control electromagnetic valve D which are connected in series by pipelines. The energy conversion system comprises a body; a working cylinder is connected with a crank gear through a piston; and a fly wheel is connected with the other end of the crank gear. The control system consists of an electronic control unit, a signal acquisition device and an execution device. The numerical control pneumatic engine uses compressed air or liquid nitrogen, and has the characteristics of no pollution, convenient storage and transportation, simple manufacturing process, high energy efficiency, convenient control and the like, and can be used as a power source for daily short traffic or indoor traffic tools in seriously polluted cities.