Boundary-layer transition measurement using temperature sensitive paint (TSP) is an effective method for studying Reynolds number effects in cryogenic wind tunnels. In this study, the cryogenic TSP boundary-layer transition measurement technique developed at the China Aerodynamics Research and Development Center (CARDC) is presented. Ruthenium-based TSP (Ru-TSP) and Europium-based TSP (Eu-TSP) were developed, which cover a temperature range of 110–320 K. A cryogenic TSP calibration system was established, which operates within a temperature range of 77–475 K with a temperature control accuracy of ±0.1 K. Using a laminar flow nacelle as the research object, a boundary-layer transition measurement test was conducted in the 0.3 m cryogenic wind tunnel at CARDC, yielding transition locations at various Reynolds numbers. The results indicate that the adhesion, emission intensity, and temperature sensitivity of TSP meet the requirements for cryogenic testing. By adjusting the flow temperature, a rapid temperature difference between laminar and turbulent flow regions on the model surface was successfully achieved. The observed changes in the transition location of the laminar flow nacelle are consistent with aerodynamic principles, thereby validating the effectiveness of the developed TSP technique for cryogenic wind tunnel applications.