The invention relates to a water pH value detection device used in an outdoor experiment course, in particular to a portable and efficient water pH value detection pen used in the outdoor experiment course, and aims to provide the portable and efficient water pH value detection pen which is used in the outdoor experiment course, is low in production cost and convenient to carry and can stimulate independent hands-on abilities of students. In order to realize the technical effects, the portable and efficient water pH value detection pen used in the outdoor experiment course comprises a pen body, a baffle, a first bearing block, a second bearing block, a first spring, a water storage frame, a cylinder, a first rotary rod, a second rotary rod, a screw rod, a first nut and the like, wherein the baffle is vertically hinged and connected to the upper part of the right side surface of the pen body. According to the portable and efficient water pH value detection pen used in the outdoor experiment course, a piston moves leftwards or rightwards by screwing a first screw, so that water is sucked or sprayed for sampling.