Herein, the effect of the angle of incidence on the characteristics of underwater plasma acoustic wave signals induced by 1064-nm nanosecond laser was studied. Result shows that when the laser is incident perpendicularly, the intensity of the laser-induced underwater plasma acoustic wave signal was the strongest. With the angle of incidence increasing, the intensity of the underwater plasma acoustic wave signal gradually decreased. Based on the plasma luminescent image, the laser-induced underwater plasma was found to exhibit multiple times of focusing. As the angle of incidence increased, the length of the underwater plasma gradually became longer, the radius of the plasma chamber gradually became smaller, and the luminescence intensity of the underwater plasma became weaker. Because of the optical refractive effect on the air-water surface, the equivalent focal length of the lens became larger and the Rayleigh length of the focusing lens was extended, thereby reducing the intensity of the laser-induced underwater plasma acoustic wave signal. The research results obtained herein have important significance in fields of laser underwater acoustic wave detection and laser communication.