Abstract: As an off-site law enforcement system, the vehicle horn monitoring system is an effective tool for traffic police to monitor and penalize illegal vehicle horn usage. This study focuses on the verification methods for such systems, particularly analyzing the sound source localization algorithm principles. It investigates the key verification items listed in the national verification regulations, including measurement error of sound pressure level, spatial resolution, positioning error, effective identification area, and the time consistency of acousto-optic images. By analyzing the localization results of sound sources at different frequencies and positions, the study identifies patterns relevant to vehicle horn monitoring systems. The results show that sound pressure level measurements should be conducted in an anechoic chamber to minimize unnecessary sound reflections. Additionally, there is an inverse relationship between spatial resolution and resolution angle at different frequencies. Positioning error is more pronounced in the Y-axis direction due to greater distance attenuation effects, resulting in larger errors compared to the X-axis direction.