The invention provides a power battery precision structural component laser welding optical field distribution control method and system. The optical field distribution control method comprises the following steps that a laser device is adopted for forming a plurality of light beams of laser formed by combining a plurality of light beams to be used as laser adopted in the laser welding process; awelding track of a power battery precision structural component in the laser welding process is obtained; in the laser welding process, according to the welding track, the optical field distribution of each light beam in the multiple light beams of laser is dynamically adjusted, and then optical field distribution of the multiple light beams of laser is adjusted. According to the power battery precision structural component laser welding optical field distribution control method, the effect of the laser on materials can be dynamically changed adaptively, the effect of controlling the temperature gradient and stress gradient is achieved, then, the problem that a welding region material is not continuous and has micro cracks in the welding process can be avoided, and the welding quality of the power battery precision structural component can be effectively improved.