Liquid cooling garments (LCGs) are considered a feasible cooling equipment to protect individuals from hyperthermia and heat-related illness when working in extremely hot and stressful environments. So far, the goals for optimization design of LCGs are mostly from the perspective of enhancing its efficiency and duration working time. However, thermal comfort is the key factor which is often not considered. In fact, there are many situations that may cause discomfort. For example, as the ice melts, the inlet temperature of the liquid cooling vest changes constantly resulting in the change of thermal states of the human body, which lead to discomfort of human. So, it is very significative to develop a method to evaluate the performance of LCGs considering thermal comfort. In this paper, an uncomfortable time ratio was proposed to evaluate the performance of LCGs considering thermal comfort. It defined the proportion of uncomfortable time including overcooling and overheating in the entire working time. Series of tests were conducted by a modified thermal manikin method to evaluate the thermal properties. According to the analyses, the duration working time was 82.77 min, while the uncomfortable time ratio was too large, up to 57.6 %. It showed that the requirement of comfort should be considered when optimizing the performance of LCGs. The influences of different parameters such as the volume of ice, flowrate, inlet temperature on the performance of LCGs were investigated through orthogonal experimental design. The statistical analysis illustrated that the influence of the volume of ice on the uncomfortable time ratio is greater than that of flowrate and ambient temperature. It is concluded that this method is useful for the control and design of LCGs considering thermal comfort.