Low-grade Thermal Energy Conversion (LTEC) system has a huge energy resource but low energy density. Because the thermal efficiency of cycle is theoretically small, it is necessary to enhance on the system performance of the LTEC system. The Multi-Stage cycle was proposed aiming at optimizing the power output from low-temperature heat sources such as geothermal or waste heat. An evaluation method for the multi-stage power generation system using an unutilized heat source has been proposed in previous studies. In this paper, it is shown on an influence of the heat source temperature and flow rate on the maximum power of Multi-Stage cycle that has independent equipment respectively. As a result, the maximum power output of Multi-Stage cycle increased approximately twice compared with a Single-Stage cycle. The maximum power output ratios of Multi-Stage cycle to Single-Stage cycle are almost same at any heat source flow rate conditions. The thermal efficiency of the cycle for the maximum power of a multistage heat engine was constant in each heat source temperature condition, regardless of the number of stages. The heat source temperature did not impact the increased maximum power efficiency, during an increased number of stages for a multistage heat engine.