In order to investigate cutting characteristics of negative plate composites, the temperature field of negative plate composite material of the lithium ion battery by laser cutting was numerically simulated based on finite element model. The size of the width and depth of the negative electrode slit was obtained from the temperature field distribution. The effect of laser power, cutting speed and spot radius on the slit width and depth of negative surface material was studied. The results show that, the width of the slit on the surface of the negative electrode increases with the increase of laser power and the radius of the spot. It decreases with the increase of cutting speed. The slit depth increases with the increase of laser power. It decreases with the increase of cutting speed and spot radius. After cutting to the middle copper foil, the change rate of the slit depth is slowing down. The composite structure of the negative electrode material has a significant effect on the depth of the slit. When the power is 170W, the radius of the spot is 47μm, and the cutting speed varies to about 600mm/s, the effect is most obvious. The cutting depth reaches 60μm under this parameter. After breaking through this threshold, the growth rate is increased significantly until the polar plate is completely cut off. The results can provide a reference for laser cutting of lithium ion battery plate composite material.