Infiltration is a key step to transform rainfall into soil water.Infiltration capacity in three typical soil and water conservation projects (88542 level furrow site preparing,fish-scale pit site preparing,and level terrace) in the loess hilly regions of Southern Ningxia Hui Autonomous Region is studied by means of double ring method.Results showed that infiltration capacity was significantly improved after implementing the soil and water conservation projects.By the capacity,the order of the three engineering measures was 88542 level furrow>fish-scale pit>level terrace.The infiltration models for the engineering measures were all accord with power-exponent equation.The changes in soil bulk density and soil porosity was the main cause of the change in infiltration capacity.The improvement degree of soil bulk density and porosity by the three measures has a high concordance with the change of infiltration capacity.