A locator comprises a first clamping element, a second clamping element opposite to the first clamping element, a guide bar extending through the first clamping element and the second clamping element, and a transmitting element rotatably disposed between the first clamping element and the second clamping element and abutting the first and second clamping elements. When the transmitting element rotates, the first clamping element and the second clamping element move along the guide bar to approach or move away each other, thereby clamping or releasing an object.