Objective To discuss the significance and mechanism of normothermic machine perfusion （NMP）for the preservation of marginal donor kidney. Methods A total number 10 small pigs were randomly divided into two groups，experimental group（n ＝ 5）：bilateral donor kidneys were preserved after 30 min of warm ischemia，and autologous kidney transplantation were performed after 7 h preservation with NMP device ；control group（n ＝ 5）：bilateral donor kidneys were preserved after 30 min of warm ischemia，and autologous kidney transplantation were performed after 7 h preservation with UW solution. At each time point，serum creatinine level， renal inflammatory cytokine expression，apoptosis，renal cortical microcirculation changes and survival rate were compared between the two groups. Results The kidneys in both groups were preserved and transplanted，and the success rate of surgery was 100%. During the period of kidney preservation, the pressure and blood flow were stable. At 24 h after transplantation，the serum creatinine level in the experimental group was significantly lower than that in the control group. The levels of ET-1 and caspase-3 in the renal tissue were decreased markedly，and the bloodflow in the renal cortex was increased significantly（P ＜ 0.05）. There was no significant difference in survival rate between two groups（P ＞ 0.05）. Conclusions NMP preservation could significantly reduce preservation damage and ischemia-reperfusion injury. The protective mechanism may result from reducing the expression of ET-1 in renal tissue and improving the microcirculation of the donor kidney，and reducing the level of caspase-3 to reduce ischemia-reperfusion injury.