To investigate the machining characteristics of vector laser fields on silicon surfaces under water assistance, a nanosecond vector laser water-assisted surface machining system was developed. A Q-switched Nd:YAG pulsed laser was used to perform laser drilling experiments on 3 mm thick monocrystalline silicon. The effects of pulse number, beam polarization state, topological charge, and water flow rate on silicon surface machining were systematically studied under both static water and water-jet assistance. The results show that under water-assisted conditions, the heat-affected zone and recast layer are almost eliminated. Compared to linearly polarized light, vector beams produce larger hole diameters at high pulse numbers. Among generalized cylindrical vector beams, radial and azimuthal polarization, and higher topological charge vector beams, the latter results in smoother hole surfaces. Under water-jet assistance, when the water flow rate exceeds 0.8 L/min, the circular symmetry of the machined hole begins to degrade. However, compared to radial and azimuthal vector beams, generalized cylindrical vector beams better maintain hole symmetry. The combination of water assistance and vector laser technology enables more precise machining, demonstrating significant potential for industrial applications.