The invention provides a bottom welding effect verification method and device for a negative tab of a cylindrical battery, and belongs to the technical field of battery fabrication. The bottom weldingeffect verification method comprises the steps of inserting a welding needle, pressing a welding needle, performing welding and energization, upwards moving a welding head and pulling out the weldingneedle; setting resistance test after welding and energization and before welding head upwards moving; and repeating welding and energization in the resistance test when an actually-measured resistance value R is more than or equal to Rm, performing secondary welding, and upwards moving the welding head to complete welding when the actually-measured resistance value R is smaller than Rm. By the bottom welding effect verification method for the negative tab of the cylindrical battery, a bottom welding effect of the negative tab of each battery can be verified in real time, an unqualified product caused by detection leakage is prevented from entering a next process, and the production quality of a battery product is improved.