In order to improve the secrecy transmission performance of visible light link, based on the analysis of link secrecy capacity under static and dynamic optical beam configurations, a security performance enhancement method of visible light communication physical layer based on dynamic vertical non-Lambertian beam is proposed, which selects the vertical candidate beam dynamically according to the different emitter, secrecy user and position relationship of eavesdropper. Quantization results show that, in a typical indoor environment, compared to a conventional static Lambertian beam configuration, the average secrecy capacity gain based on dynamic vertical non-Lambertian beam configuration is up to 3.03 b·s-1·Hz-1, and the gain ratio is up to 86%.