The invention relates to a clamping method and device, in particular to a clamping method and device for balancing a locking force from bottom to top. The invention belongs to the technical field of machining and clamping of metal parts. Each machining workpiece is placed on an end surface of a corresponding clamp body, a workpiece connecting positioning hole in each machining workpiece is completely aligned to a clamp body connecting positioning hole in the corresponding clamp body, effective balanced locking between each machining workpiece and the corresponding clamp body is realized by a corresponding locking screw and a corresponding spring washer, a workpiece in which high-precision form and location tolerance exists between the outline and an irregular cavity can be clamped effectively, clamping operation is facilitated, and the clamping method and device are safe and reliable.