Provided herein is a method for constructing a pumping-injection well of a groundwater reservoir in a dump of an open-pit mine. The pumping-injection well includes a bottom pipe, intermediate pipes, and a top pipe in sequence from bottom to top connected from bottom to top. The method includes: arranging a rubble barrier around the pumping-injection well, and installing the bottom pipe of the pumping-injection well at a designed position of the pumping-injection well as a center of circle; continuing to install an intermediate pipe on the bottom pipe, and pile up a rubble pile; continuing to stack multiple intermediate pipes, and starting the construction of the groundwater reservoir; discarding discarded materials from the open-pit mine to form a dump; continuing to stack intermediate pipes to build an inverted trapezoidal surface sump around the pumping-injection well; and installing the top pipe and a well cover to form a complete pumping-injection well.