In the paper, 32 lots of intravenous immunoglobulin (IVIG)were tested by an animal model,the hypotensive test of rats. A linear correlation was found between prekallikrein activator (PKA)activity and hypotensive reaction if the inflow of human IVIG was made rapid (r=0.96,n=23). The preliminary observations indicated that it would be satisfactory that the PKA activity was below 35IU/ ml and the size of reduction in blood pressure was not 15% higher than that of control animal's level.The rat model can provide a method for safe usage of the intravenous immunoglobulin and reliable detection of and control over the residual PKA activity in blood products.