The invasive species are believed to perform better than native species in many aspects of physiology and behavior. Thermal physiological performance, one of the most crucial traits potentially determining the invasion success of alien species, has only been investigated experimentally in a few comparative studies of invasive and native species.In order to assess the superiority of some functional performances in invasive turtles over native ones, we incubated 160 eggs of Trachemys scripta elegans and Mauremys reevesii from two different cultured cohorts (Haikou-a low-latitude site and Haining-a high-latitude site, 40 eggs from each cultured cohort of both species) under an identical laboratory condition[(29±1)℃, -220 kPa substrate water potential], and randomly selected 80 hatchlings (20 individuals from each cultured cohort of both species) to measure their locomotor performances (swimming speed and righting time) and heart rate at seven different test temperatures (16, 20, 24, 28, 32, 36 and 40℃). A laterally positioned digital video camera was used to record the swimming performance of each turtle in a racetrack with 10 cm water depth in the swimming tests, while a perpendicularly positioned camera was used to record the righting performance of each turtle in an open box in the righting tests. Videoclips were examined later for the average swimming speed over 30 cm, and righting time. An infrared heart rate monitor was used to measure the heart rate (beat per minute) of each turtle. Test temperature significantly affected swimming speed, righting time, and heart rate in hatchlings of both turtle species. T. scripta elegans hatchlings appeared to have a greater swimming speed and heart rate, but needed more time to right themselves than M. reevesii hatchlings. Individuals from the Haikou cohort had a greater swimming speed, heart rate, and shorter righting time than those from the Haining cohort. We used the curve-fitting procedure of TableCurve 2D to construct thermal performance curves (TPCs) based on the exponentially modified Gaussian model for each locomotor and physiological variable, and then extracted two parameters[the maximal performance (P_m) and thermal performance breadth at 80% level of maximal performance (B₈₀)] from each constructed TPC. Similarly, T. scripta elegans hatchlings had a higher P_m for swimming speed and heart rate, but lower P_m for the reciprocal of righting time than M. reevesii hatchlings; individuals from the Haikou cohort had a higher P_m for swimming speed, heart rate and reciprocal of righting time than those from the Haining cohort. T. scripta elegans hatchlings had a wider B₈₀ for swimming speed than M. reevesii hatchlings, but not for heart rate and reciprocal of righting time;individuals from the Haikou cohort had narrower B80 for swimming speed and reciprocal of righting time than those from the Haining cohort. These results probably indicated that T. scripta elegans had better locomotor and physiological performances (e.g., faster swimming speed and greater thermal plasticity) than M. reevesii, which might contribute to its invasive success in a novel environment. Compared with M. reevesii hatchlings, T. scripta elegans hatchlings righted themselves more slowly, probably due to their more flattened body shape.