Abstract: Objective: To explore the effect of decelerating the addition of RBC additive solution on prolonging the shelf life of RBC and provide the reference on delay release technic. Methods: 12 bags of packed RBC were collected, each was averagely divided into 4 bags（groups）. The control group was added standard MAP additive solutions and the other three groups were added MAP in different proportion. Then they were stored at 25 ℃（4 ℃） with in vitro testing for some items as ATP etc daily. During the preservation, each of the experiment groups was continually added MAP at different rate till total MAP was same as control group. Results: RBC can not be effectively stored only if it was added enough additive solution before preservation, ATP in RBC can be kept more longer in the groups with MAP gradually added than the control group with MAP added one time and the same result happened in the groups with MAP added slowly better than those with MAP added fast. Conclusion: Decelerating the addition of RBC additive solution can effectively prolong RBC’s shelf life, it suggest that delay release technic can be applied in RBC preservation and has the value of research.