Abstract: In order to optimize the spot shape of the photoacoustic imaging system, the method of collimating the traditional circular spot and converting it into a linear spot was used to analyze and verify the experiment. The double-convex lens was designed by software to collimate the laser beam, and the average divergence angle of the beam was reduced to 26%. The corrugated lens was used instead of the traditional cylindrical lens, and the circular spot was effectively converted into a linear spot through the diffraction effect, which makes the spot energy distribution more uniform and expands the scanning range, thereby improving the stability and consistency of the experiment. The results show that the collimated laser beam forms a uniform spot with the same width at different distances, and the average width of the spot is about 10 mm, while the uncollimated beam has a large divergence angle, and the average width of the beam is 20 mm. After adding a corrugated lens to convert the circular spot into a linear spot, the spot size of the linear spot remained basically unchanged at the distance of 4 cm and 8 cm, and the application of the linear spot significantly expanded the imaging range and coverage area. This approach is in stark contrast to previous studies that used cylindrical lenses and traditional laser techniques. The optimization of the laser light source in photoacoustic imaging provides an effective guarantee for the photoacoustic imaging effect.