A study of conservation tillage was conducted in the semi-arid area of the west Loess Plateau, Gan- su Province, to determine the eff ects of diff erent tillage measures on soil water infiltration.Results show that no-tillage with straw cover(NTS) can improve soil structure property, soil organic carbon content, and soil water infiltra tion.Path coeff icient analysis indicates an improvement of soil water infiltration due to the increase in soil macro-porosity and total organic carbon content.The contribution of total organic carbon to soil water infilt ration is also essential to soil macro-porosity.