A self-locking device having continuous locking positions comprises bases (21, 31), self-locking components (22, 32), first locking blocks (23, 33, 33′) and second locking blocks (23a, 33a, 33a′). Inner walls of the bases (21, 31) comprise first frictional contact surfaces (21W, 31W) and fourth frictional contact surfaces (21M, 31M). The self-locking components (22, 32) have second frictional contact surfaces (22M, 32M) and third frictional contact surfaces (22W, 32W), and are at least partially located in the bases (21, 31), so that the second frictional contact surfaces (22M, 32M) face the first frictional contact surfaces (21W, 31W), and the third frictional contact surfaces (22W, 32W) face the fourth frictional contact surfaces (21M, 31M). The first locking blocks (23, 33, 33′) are disposed between the first frictional contact surfaces (21W, 31W) and the second frictional contact surfaces (22M, 32M), and contact the first frictional contact surfaces (21W, 31W) and the second frictional contact surfaces (22M, 32M). The second locking blocks (23a, 33a, 33a′) are disposed between the third frictional contact surfaces (22W, 32W) and the fourth frictional contact surfaces (21M, 31M), and contact the third frictional contact surfaces (22W, 32W) and the fourth frictional contact surfaces (21M, 31M). The first locking blocks (23, 33, 33′) and the second locking blocks (23a, 33a, 33a′) are in such a structure that the self-locking components (22, 32) are capable of moving along a first direction (F1) relative to the self-locking bases (21, 31) under the effect of an external force, and are locked in a second direction (F2) opposite to the first direction (F1). In this way, the self-locking components (22, 32) can be locked at any one of the continuous locking positions. Also disclosed is a tool (7A-7C) for locking and unlocking the self-locking device. The self-locking device is capable of implementing fast locking and unlocking, which is convenient to use.