Abstract: To address the need for ammonia detection in industrial and agricultural applications, a real-time ammonia detection system was developed. V₂C MXene/V₂O₅ composite films were synthesized through etching and heat treatment using V₂AlC as the primary material, and the ammonia sensor was fabricated using a spraying technique. The gas-sensing performance of the film sensor was evaluated at varying ammonia concentrations. The findings indicate that the composite film sensor exhibits significant sensitivity to ammonia gas. Hardware circuit design and program development were performed to address sensor temperature and humidity errors as well as signal processing. A differential measurement circuit was implemented to minimize temperature and humidity errors. Two operational amplifiers were utilized to construct instrumentation amplifiers for the amplification of input differential signals. Based on STM32 and LabVIEW, the ammonia detection device was designed and fabricated. This device is capable of real-time ammonia concentration detection, data storage, and over-limit alarming, offering the benefits of straightforward operation and high practicality.