Water conservation capacity of the different plant communities were compared in north region of Yanshan mountain.The results showed that the interception by litter contributed most in the total interception of the aboveground layers.For total interception of aboveground vegetation layer,the plant communities were ranked in a descending order as follows: larch plantation(4.39 mm)natural secondary poplar and birch forest(3.81 mm)Corylus heterophylla shrub(1.7 mm)Spiraea pubescens shrub(0.18 mm).Both soil water holding capacity and total soil porosity of Corylus heterophylla shrub were the biggest,followed by natural secondary poplar and birch forest,larch plantation,and Spiraea pubescens shrub.In terms of soil infiltration,natural secondary poplar and birch forest had the highest rate,larch plantation and Corylus heterophylla shrub had similar intermediate rates,and Spiraea pubescens shrub had the lowest.The total amount of water conservation of the plant communites in a descending order was Corylus heterophylla shrub(272.52 mm)natural secondary poplar and birch forest(239.61 mm)larch plantation(221.53 mm)Spiraea pubescens shrub(194.85 mm).The amount of aboveground vegetation layer interception accounted only a very small portion of the total water conservation for all the communities,showing little importance in their overall water conservation capacity.It is concluded that Corylus heterophylla shrub and natural secondary poplar and birch forest are of critical values in water balance of the region,while the water conservation value of Spiraea pubescens shrub is low owing to frequent human and animal disturbances.As Spiraea pubescens shrub is widely distributed,some reasonable measures should be carried out to improve overall water conservation in this region.