Abstract: Hypersonic vehicles inevitably encounter extremely intricate and highly variable meteorological conditions during flight. As flight speed increases, the impact of suspended ice crystal particles on the vehicle’s surface structure grows exponentially. T causing severe erosion to thermal protection and structural surfaces, altering aerodynamic performance, and undermining flight stability and maneuverability. Droplets represent one of the most significant and widely distributed forms of ice crystal particles existing in high-altitude atmospheres. In-depth investigation of the dynamic interaction process between high-speed gas flows and micro-droplets can reveal complex flow patterns and underlying physical mechanisms that govern gas-liquid coupling phenomena. Moreover, the accurate and reliable experimental characterization of key droplet parameters—such as transient temperature and spatial diameter distributions—serves as an indispensable prerequisite and fundamental foundation for studying gas-liquid interaction behaviors under high-altitude, low-pressure environmental conditions. This study develops a novel simultaneous measurement method that is specifically designed to characterize critical liquid-phase parameters, particularly droplet temperature and diameter in low-pressure environments, by utilizing the two-color laser-induced fluorescence (2c LIF) technique, thereby providing robust and reliable measurement support for advanced gas-liquid interaction research under high-altitude, low-pressure conditions. Temperature-sensitive Rhodamine B (RhB) and relatively temperature-insensitive SulfoRhodamine 101 (SRh101) fluorescent dyes are carefully and deliberately employed to construct both single-dye and mixed-dye measurement systems with optimized configurations. A thorough and systematic investigation is conducted to evaluate the quantitative influence of key experimental factors, including dye concentration, laser pulse energy, and ambient pressure, on the calibration relationship and fluorescence spectral characteristics of the system. Quantitative linear and nonlinear relationships between the fluorescence intensity ratios and the corresponding droplet temperature are precisely established for each dye configuration by selecting two distinct and non-overlapping spectral bands. Furthermore, high-resolution two-dimensional imaging of micro-droplets under varying temperature conditions is carried out, with advanced image processing techniques applied to extract the detailed spatial distributions of droplet diameter and temperature. Experimental measurement deviations and their primary influencing factors are comprehensively and systematically analyzed. The final experimental findings clearly suggest that the 2c LIF technique enables effectively and accurately facilitates the non-intrusive measurement of multi-parameter droplet characteristics in low-pressure environments.