Dy namics of soil moisture in root layer , water use efficiency , crop yield, and economic benefit sunder different types of conservation tillage were studied with the triple crops of wheat-maize-sweet potato in the southwest China .Results indicated that different types of conservation tillage had significant effects on cropyield and water use efficiency .Straw mulching (TS), film mulching (TM), straw mulching plus film mulching (TSM), and ridge plus straw mulching plus film mulching (RSM)increased soil water storage and soil moisture in 0—60 cm soillayer in July and October , while ridge (R), ridge plus straw mulch (RS), and ridge plus film mulching (RM)can not remarkably affect the indexes .RSM , RM , RS , TSM , TM , TS , and Rincreased average yield by 0 .52 %, 6 .11 %, 6 .77 %, 4 .59 %, 5 .12 %, 3 .15 %, and 1 .24 %, respect ively ,compared with CK .T he comprehensive effect of ridge plus straw mulching plus film mulching was the best in view of water use efficiency , rainfall use efficiency , cropyield , and economic benefits.