The effects of dietary calcium level on dry matter intake, milk yield, blood and urine parameters were observed in the present experiment to investigate an optimum calcium level in diets of early lactating dairy cows. Four Holstein cows ［lactating for three months, milk yield (20.33±0.92) kg］ were used in a 4×4 Latin square experiment. Dietary calcium levels of the four treatments were 0.50%, 0.68%, 0.83% and 0.96% (DM basis), respectively. The results indicated as follows: 1) dry matter intake of 0.50%, 0.68% and 0.83% treatments was significantly higher than that of 0.96% treatment (P<0.05), but there were no significant differences among 0.50%, 0.68% and 0.83% treatments (P>0.05); milk yield of 0.68% treatment was significantly higher than that of the other groups (P<0.05). 2) With dietary calcium level increasing, apparent calcium digestibility of lactating dairy cow was decreased, but the concentrations of feces calcium and urine calcium were increased, and the apparent calcium digestibility of 0.50% treatment was significantly higher than that of the other groups (P<0.05), while urine calcium/urine creatinine of 0.50% treatment was significantly lower than that of the other groups （P<0.05）, but there was no significant difference between 0.68% and 0.83% treatments (P>0.05); feces calcium concentration of 0.96% treatment was significantly higher than that of 0.50% treatment （P<0.05）, but there were no significant differences among 0.50%, 0.68% and 0.83% treatments (P>0.05). 3) With dietary calcium level increasing, blood pH and urine pH were increased (P<0.05), and 0.96% treatment was significantly higher than 0.50% treatment （P<0.05）, but there were no significant differences among 0.50%, 0.68% and 0.83% treatments (P>0.05). 4) With dietary calcium level increasing, plasma ALP activity, CT and BGP concentrations were increased, and 0.96% treatment was significantly higher than 0.50% treatment (P<0.05), but there was no significant difference between 0.68% and 0.83% treatments (P>0.05); plasma PTH concentration was decreased, and 0.50% treatment was significantly higher than the other groups (P<0.05). In conclusion, the optimum dietary calcium level for early lactating Holstein dairy cows is 0.68% (DM basis).［Chinese Journal of Animal Nutrition, 2010，22（5）:1286-1292］