Gas-liquid separation technology is one of the key technologies of environmental control and life support in manned spaceflight. In order to realize gas-liquid separation under microgravity, a prototype of a gas-liquid separator based on passive static separation technology was designed, manufactured, and studied by both ground experimental tests and computational fluid dynamics (CFD). Results show that the experimental results on earth are in good agreement with the simulation results and the internal fluid distribution directly determines the separation rate of the separator. The separation rate and internal flow field of the separator were also investigated under various flow rate conditions and gravity levels. Results show that higher liquid flow rate and lower gravity level can improve gas-liquid separation rate which attributes to the formation of a complete liquid film at the bottom of the collector. The separation rate can reach 100% within the specific ratio range, and the structure of the equipment is simple, without any power components, meeting the requirements of long life and high reliability of space equipment. It can provide a reference for gas-liquid separation in space under the microgravity environment.