The paper studied the effect of rainwater harvesting planting measure with mulched ridges on growth and development of Elymus sibiricus L. In northern agriculture-animal husbandry ecotone. It suggested that rainwater harvesting with mulched ridges could make the limited rainfall converged abundantly in the furrow, and the efficiency of ridge surface running amounts to about 80%. In vegetative growth stage of E. Sibiricus L. In 2008 and 2009, the differences of the height in treatments were significant respectively (P<0.05). In 2008, the plant height in MR60 increased by 33.5%～61.3% compared with CK, MR30 increased by 20.1%～44.1% compared with CK, and MR60 increased by 9.2%～16.2% compared with MR30. In 2009, the plant height in MR60 increased by 93.2%～116.4% compared with CK, MR30 increased by 65.4%～82.3% compared with CK, and MR60 increased by 12.1%～19.4% compared with MR30. The differences of density among MR30, MR60 and CK were not significant, but the MR30 and MR60 both were higher than CK, generally.Density dynamics kept the same pace with the variation of average tillers in 2008, the density wholly decreased slowly and tended to stable after turning green in 2009.