Abstract: Temperature is one of the most important environmental factors that impact the physiological activities of fishes. Fishes exhibit thermal tolerance, which are influenced by temperature acclimation. Global climate change is one potential factor affect the survival and growth of fish species. Therefore, investigation of thermal tolerance of various fish species is of great importance. Rhynchocypris oxycephalus is a typical cold-water fish that might be influenced by the future global warming. The current study investigated thermal tolerance of R. oxycephalus using critical thermal methodology by acclimating the fish to 14, 19, 24 and 29℃ temperature for two weeks. The results showed that thermal tolerance of R. oxycephalus regulated by temperature acclimation, and that the critical thermal maxima (CT_max) increased with the increase of temperature acclimation, and that the average CT_max were 32.29, 33.23, 33.40 and 35.71℃. The critical thermal minima (CT_min) decreased with the decrease of temperature acclimation, and the average CT_min were 0.00, 0.10, 2.10 and 5.27℃. At the moderate acclimation temperature (19℃), R. oxycephalus has the widest thermal tolerance up to 33.13℃. The higher acclimation temperatures produced higher acclimation response ratio (ARR). The maximum ARR (0.46) of high temperatures occurred in the range of 24—29℃, while the maximum ARR of low temperatures, (0.63) occurred in 29—24℃. A thermal tolerance polygon in the range of 14 to 29℃ showed an area of 478.98℃², which was similar with eurythermal fishes. These results indicated that R. oxycephalus has strong ability for thermal adaption.