In water jet guided laser processing technology, high-quality beams play a key role in coupling efficiency. In order to solve the problem of water-optical coupling technology, the water jet guided laser processing technology can be better used in high-precision and low-damage processing of materials with high melting point and high hardness and brittleness, and the self-focusing-ball lens combination focusing mode and positive-negative axicons focusing mode are compared and analyzed with the traditional convex lens focusing mode. According to the three applicable focusing modes, the corresponding ABCD transmission matrix is derived, the beam characteristics under the focusing mode are simulated, and the characteristics of industrial applications under different focusing modes are discussed. The simulation results show that the beam waist radius of the combined positive-negative axicon lens is the smallest, the divergence angle of the beam after the traditional convex lens focusing mode is the smallest, and the three modes have different structures, and they all have their own advantages and disadvantages.