Abstract: We used Heilongjiang grass lizards (Takydromus amurensis), which were collected from Changbai Mountain, as model animals. These lizards were housed to breed in the laboratory from April to June, 2014. In early October, adult and juvenile lizards were placed in the constant temperature incubator for measurement of body temperature. The effects of different temperature conditions (constant temperature and rapid warming) on body temperature and thermoregulation ability of T. amurensis were studied. The measuring time had significant impacts on the body temperature of T. amurensis from 11 to 39 ℃, and the lowest body temperature appeared at 07:00 a.m. The body temperature was significantly higher in juveniles than in adults from 11 to 19 ℃. There was no difference in the body temperature between juveniles and adults at 21 ℃; the body temperature was significantly lower in juveniles than in adults from 23 to 39 ℃. The body temperature of T. amurensis was linearly positively correlated with ambient temperature. The linear regression equations were as follows: y=0.72366x+7.1778 for the adults, and y=0.6508x+8.8039 for the juveniles, whose intersection point temperatures with isothermal line (y=x) were 25.97  and 25.21 ℃, respectively. The body temperature of T. amurensis increased in a short time with the ambient temperature increased rapidly from 10  to 30 ℃, but the heating rate gradually decreased. We concluded that the ambient temperature had a significant impact on body temperature of T. amurensis, and the thermoregulation ability of different aged lizards was different. Juvenile lizards had stronger thermoregulation ability, thus they could keep their body temperature stable more easily than adults.