The single-channel-serpentine proton exchange membrane water electrolyzer (PEMWE) has the potential to be a crucial element in the linking of power, transport, heating, and chemical industries in the foreseeable future of sustainable energy systems. Its performance is influenced by a number of factors. Within the many factors affecting their performance, the external operating parameters have a significant effect on the temperature distribution of the internal components as well as the moisture distribution. In this paper, a single-channel-serpentine flow field electrolyzer (SFFE) is built to address the simulation deficiencies of a conventional single-channel proton exchange membrane electrolyzer, and to more intuitively represent the effects of single-channel-serpentine external environmental parameters on the internal performance of the electrolyzer, in order to assess the effects of different voltages, operating temperatures, and inlet flow rates on the distribution of heat, the distribution of liquid water and gases, and the susceptibility to cross-penetration sites. The results show that when the operating voltage drops below 2.2 V, the liquid-saturated water undergoes a greater impact. Specifically, the voltage increase from 1.6 to 2.2 V results in a significant decrease from 0.97 to 0.79, corresponding to an 18.6% drop. That is, when the voltage is 2.2 V, the liquid water content ensures the adequacy of the reaction, while the inhibitory effect of bubble formation occurs at the beginning. Therefore, 338.15 K and 2.2 V are the most recommended experimental conditions.