A clamping and positioning device includes a base, a rotary member, a moving assembly and an elastic member. The rotary member is rotatably disposed on the base and includes a stopping surface facing the base. The moving assembly includes a moving member movably disposed on the base to have a first and a second position. When being at the first position, the moving member is pressed against the rotary member to allow the stopping surface to apply a normal force to the base; when being at the second position, a gap is formed between the moving member and the rotary member so the normal force applied by the stopping surface of the rotary member is released from the base. The elastic member has two ends connected to the base and the moving member, respectively. The elastic member normally causes the moving member to be at the first position.