A method for the design and operation of a heat-recovery ground-source heat pump (HR-GSHP) system has been investigated. In this paper, a designmethod for the HR-GSHP system by applying the optimization method was first introduced. By applying the design method, the total heating and coolingloads of each ground-source heat pump (GSHP) unit in the HR-GSHP system were maximized in response to an arbitrarily set total length of theground heat exchanger (GHEX). This means that the HR-GSHP system designed with the design method could yield the maximum energy saving effectfor a given GHEX total length. Next, it was assumed that the HR-GSHP system with a 7,200-m total GHEX borehole length was installed in alarge scale complex building, which required both heating and cooling at the same time throughout the year, and the hourly heating and cooling loads ofeach GSHP unit was determined using the design method. As a result, it was confirmed that the HR-GSHP could cover approximately 4.3 times theheat load of a conventional GSHP system. In addition, the simulation of annual HR-GSHP system operation was performed using the design andperformance prediction tool for the GSHP system. The hourly heat load determined by the design method was given in the simulation. The averagecoefficients of performance (COP) for the HR-GSHP system were 4.6 for heating and 10.3 for cooling. Thus, the HR-GSHP system was advantageousin not only the amount of heat load that could be covered but also the COP compared to the conventional GSHP system.