For the system of Lithium Bromide Absorption Heat Pump(LBAHP), parameters that affect the performance of LBAHP are researched in the process of thermodynamic cycle, including the pressure of driving heat source, the temperatures of inlet and outlet cooling water, and refrigerant water temperature. The overall COP of the system under different operating conditions is calculated by control variable. Accordingly, COP would be changed when the above four parameters is converted, the calculation results indicated that COP is increased with the rising of the pressure of driving heat source and refrigerant water temperature, while COP decreased as the temperatures of inlet and outlet cooling water went up.