The invention discloses an underground chemical reagent storage box. The storage box comprises a first box body with the top provided with an opening and a second box body fixedly arranged on the topof the first box body. The bottom of the second box body is provided with an opening. A box door is hinged to the second box body. First sliding grooves are formed in the inner walls of the two sidesof the second box body. Second sliding grooves are formed in the inner walls of the two sides of the first box body. The same containing plate is arranged in the first box body and the second box bodyin a sliding manner. Sliding blocks are fixedly arranged on the two sides of the containing plate. The sliding blocks are in sliding connection with the side walls of the corresponding first slidinggrooves and the corresponding second sliding grooves. Moving grooves are formed in the bottom inner walls of the two second sliding grooves. Installing plates are fixedly arranged at the bottoms of the two sliding blocks. Through the storage box, a reagent can be conveniently taken and placed, and time and labor are saved; under the mutual locking action of locking blocks and fixing plates, storage plate position adjustment can be achieved, reagents at different heights can be conveniently stored, and operation is simple.