Effects of constant high sustained temperature on serum biochemical parameters and muscle nutrient contents of growing pigs were investigated in this study. Nine healthy male pigs with similar genetic backgrounds (Large White×Landrace) and average initial body weight of (30.00±1.16) kg were divided into three treatments randomly: constant high sustained temperature at 33 ℃ with ad libitum feeding (group 33AL), constant optimal sustained temperature at 23 ℃ with ad libitum feeding (group 23AL), and constant optimal sustained temperature at 23 ℃ but with limited feeding with the amount equal to what was consumed by the group 33AL (group 23PF). The experimental period lasted for 21 days. The results showed that: 1) serum total protein (TP) content of group 33AL was significantly lower than that of group 23AL on the 21st day (P<0.01); some serum parameters of group 33AL were lower than those of group 23AL, and these parameters were TP content on the 1st day, globulin （GLB） content on the 2nd day, glucose (GLU) content on the 1st day, total cholesterin (TCHOL) content on 2nd and 4th day, triacyl glycerol (TG) content on the 1st day (P<0.05); 2) compared with group 23AL, dry matter (DM) and intramuscularly fat (IMF) contents in longissimus dorsi muscle of group 33AL were lower, while crude protein (CP) content was a little higher, although there were no differences (P>0.05). In conclusion, constant high sustained temperature resulted in a distinct decrease of serum TP content, and declines of DM and IMF contents while an increase of CP content in longissimus dorsi muscle of growing pigs.［Chinese Journal of Animal Nutrition, 2010，22（5）:1207-1213］