Abstract: Up-conversion board fitted on the lens could enhance the efficiency of CCD acquisition for low-frequency narrow-pulse laser spot because it is capable of changing infrared light into visible light. The up-conversion board made by traditional craft causes internal diffuse reflection and partial saturation effect which leads to the distortion of laser spot shape and intensity distribution. We put forward a new craft called lattice up-conversion board technique, and designed an experiment to compare the photographs acquired by the two crafts. The experimental results show that the lattice up-conversion board has better acquisition on low-frequency narrow- pulse laser spot. In order to evaluate the photographs of the laser spot acquired by lattice up-conversion board, a corresponding model is established.