The trial was conducted to study the effects of dietary copper levels of different sources on copper deposition and histopathological changes of liver of broilers. Two hundred and eighty-eight 1-day-old broilers were randomly divided into 8 groups, and there were 6 replicates in each group and 6 broilers in each replicate. The coppers were from CuSO4 and Cu-Met and they were respectively designed to four dietary levels containing control (11 mg/kg) and high levels (110, 220 and 330 mg/kg). The trial lasted for 60 days. The blood samples were obtained at 12, 36 and 60 d respectively to investigate ALT and AST activities, and the liver samples were processed at 60 d to investigate copper deposition and histopathological changes of broiler. The results showed that liver copper deposition of broiler in groups of two copper sources tended to increase with the increasing of dietary copper levels, and it was higher than that in control except that of 12 day-old broilers in Cu-Met group when dietary copper level was 330 mg/kg (P<0.05), and it had the effect of age-dependent; compared between the two copper sources, liver copper deposition of 36 and 60 day-old broilers in CuSO4 group was lower than that in Cu-Met group except that in control (P<0.05). The activities of ALT and AST in serum tended to increase with the increasing of the dietary copper level and age of broilers, and 220 and 330 mg/kg copper increased significantly the activities of ALT and AST in serum of 36 and 60 day-old broilers compared with the control; compared between the two copper sources, the activities of ALT and AST in serum of 36 and 60 day-old broilers in 330 mg/kg Cu-Met group was higher than that in 330 mg/kg CuSO4 group (P<0.05). At 60 days old, high dietary copper levels caused some obvious histopathological changes of hepatocyte swelling, granules degeneration in cytosolic, fuzzy structure of hepatocyte cable and liver sinusoidal under light microscope, and presented engulfing vesicle in cytosolic, fuzzy mitochondrial membrane and irregular shape, electron density deposition body in cytosolic and nucleus under electron microscopy. The results indicated that high dietary copper levels could increase the liver copper deposition, suppress the liver function and result in pathology damage of liver. At the same level, the supplementation of copper from Cu-Met could cause more liver copper deposition and more serious pathology injury of liver than that from CuSO4.［Chinese Journal of Animal Nutrition, 2010，22（1）:39-45］