The applicability of the Curve Number Method (SCS-CN) in different land use patterns was discussed to provide some references for the evaluation of water and soil conservation measures by this method. Based on the monitoring data of runoff plots in semi-arid areas of Northeast China

the feasibility of SCS-CN method in evaluating soil and water conservation measures and tillage methods was analyzed by the methods of simultaneously calibrating of runoff curve number (CN) and the initial loss ratio. The results showed that:(1) Under the drought (AMC1) condition

the optimal value of λ was 0.05

but the simulation results of different land use patterns was not ideal

while the results of bare land

contour ridge and ridge along slope simulated by the modified method of the potential maximum retention (S) were better

and the corresponding CN1 values were 87.54

68.49 and 60.46

respectively

and the optimal value of λ was 0.40. (2) The results of horizontal troughs

vegetation belts and terraces were not ideal

and the calculated values were too large when the measured runoff was more than 10 mm. The simulation accuracy was greatly improved through correcting by runoff coefficient ratio

which was recommended as a suitable correction method for water conservation measures. (3) Under normal (AMC2) and wet (AMC3) conditions

the amount of data was limited

keeping the optimum value of λ remained

correcting S value

the simulation result was ideal

and it was a suitable estimation method for arid areas.