The uniformity of the light source in contact angle measurement systems directly influences the accuracy of droplet image acquisition, which subsequently impacts the reliability of contact angle measurements. However, systematic studies and designs aimed at achieving optimal light source configurations in domestic contact angle equipment are currently insufficient. This study aims to achieve high uniformity and low cost by employing the particle swarm optimization (PSO) algorithm. Through practical analysis, an optimal arrangement of light source modules and control systems is developed. Using a contact angle standard plate, the variance, mean square error, and relative error are calculated as 30°, 60°, 90° and 120°, and the gray scale of the picture is obtained. Compared with the data measured by other methods, the results demonstrate that the design is reliable and can be used to measure the light source of portable contact angle equipment within the industry.