Abstract: A convenient weight-adjustable dumbbell, comprising a handle, and two rotating disks, two connecting disks, and two fixed blocks, a flexible shaft is connected to the side of each rotating disk, the flexible shaft surrounds the center of the rotating disk, and the other end of the flexible shaft runs through the connecting disk and the fixed block, an outer side of each fixed block is detachably connected with at least one weight block, one side of each weight block is connected with a lock for connecting the fixed block, the other side of each weight block is provided with a second slot, and each weight block is provided with a insertion hole for—the flexible shaft to pass through.