Pseudo soldering with a normal appearance and electrical connections cannot be effectively detected by the existing detection technology. Pulse infrared detection technology was applied, and the trend that analyzes processes was adopted to establish the relationship between the degree of pseudo soldering and characteristic parameters of the infrared fitting curve. It is difficult to distinguish the background noise, and the signal of the pseudo soldering from excess temperature was successfully resolved. Results show that the resolution and signal-to-noise ratio were improved.