Abstract: In order to solve the problem that low fluorescence permeability temperature will influent the sensitivity of fluorescent penetrant, the physical parameters such as viscosity and so on were tested, and the relationship between temperature, viscosity, fluorescence penetrant detection technology and water treatment was understood. The results show that the temperature range of 15~35 ℃ is suitable for penetrant inspection. Finally, a scheme for improving the temperature of the fluorescent permeation tank is proposed to ensure the sensitivity of the penetrant inspection.