Abstract: Through the practical application case, the infrared thermal imaging technology in the application of ammonia refrigeration system was introduced. It is necessary to point out that this technology has irreplaceable advantages in equipment insulation condition assessment, leak detection, level judgment, electrical equipment malfunction of heating, the investigation of hidden danger to the safety. The technology also provides scientific basis for early diagnosis and preventive maintenance of the equipment, and has very good application value in the investigation of hidden danger to safety in ammonia refrigeration system.