A blood sampling device contains: a body, a fitting sleeve, a triggering block, a trigger spring, and a switch. The body is hollow and fits with the fitting sleeve which includes an exit for extending a lancet out of the exit, and the body includes a first fixing position and a second fixing position. The first fixing position is an untriggering position away from the exit, and the second fixing position is a triggering position close to the exit. A first end of the triggering block abuts against the trigger spring, the triggering block includes a connecting orifice for accommodating the lancet and includes an elastic piece retaining at the first fixing position or the second fixing position. The switch is mounted on the body and includes a releasing segment corresponding to the first fixing position so as to release the elastic piece from the first fixing position.
