The invention discloses an apparatus for detecting precision of a pressure scan system sensor in real time. Pressure transducers acquire pressure outputted by a sensor calibration system and send the pressure to a multi-path converter, and simulation pressure data is obtained. Through an AD converted, digital signal pressure data is obtained, through pressure scan acquisition system serial scanning, real-time pressure data is obtained, and simultaneously through high speed parallel acquisition card parallel acquisition, parallel data is obtained and transmitted to an industrial controller. The industrial controller transmits the parallel data to a pressure calibration source, pressure calibration is carried out on each pressure transducer respectively, and calibration data is obtained. The industrial controller takes the calibration data as a pressure standard, carries out precision grade detection on corresponding real-time pressure data, and detects a precision grade of the pressure transducers respectively. According to the invention, detecting precision of the pressure scan system sensor in real time can be carried out, a method is simple and reliable, and practicality is strong.