Abstract: Stalagmite has the advantage of high precision dating in paleoclimate reconstruction because of the advance in TIMS-U series dating.However,the measured ages of stalagmite usually don't accord with the nature rule of stalagmite growth,which makes alot of measuredages can't beused.Taking stalagmite LL1 got in the Lianhua Cave in Longshan,west of Hunan province as an example,this study found that the quantity of ²³⁸U、²³⁰Th reduce and measuredages of stalagmite grow young in the process of the change of stalagmite structure,especially the process of wenshi changed into calcite and calcitere-crystallization. What's more,based on the condition that eliminates potential affecting factors such as sample pollution, this study calculated the calibration age of LL1 the on the assumption that the ²³⁰Th/²³⁸U lost rate is 1%, 10%,50% respectively.The result shows that the rate of lost ²³⁰Th/²³⁸U is similar to the rate of reducedage caused by the change of stalagmite structure.In addition,we find that the older the stalagmite,the younger measuredages grow compared with the realages of stalagmite.Therefore,The study on the method of the correction of TIM S-U seriesages helps to establish normal and precise stalagmite chronology.