Abstract: Objective To study the biological characteristic values of human angiotensin-converting enzyme II (hACE2)-KI/ NIFDC mice. Methods Ten hACE2-KI/ NIFDC female mice at 4 and 8 weeks of age were tested for 11 organ coefficients, 22 physiological values and 13 biochemical values. Statistical method were used for data analysis. Results The 4-week-old mice had higher values than the 8-week-old mice in five organ coefficients ( spleen, lung, thymus, left kidney, right kidney, P<0. 01) and three physiological values (mean corpuscular volume, mean corpuscular hemoglobin, eosinophil granulocyte, P<0. 05). However, in the 4-week-old mice, the other five values were below those of the 8-week-old mice ( percentage of monocyte, alkaline phosphatase, P<0. 05; heart organ coefficients, aspartate transaminase, phosphorus, P<0. 01). Conclusions These findings may provide support for the application of hACE2-KI/ NIFDC mice .