Abstract: Natural test technicses,such as liner logging,annulus logging and pump pull out logging,have a lot of limitation in yanchang epoch reservoir.Natural test ways have long close well time, affect yield of well,test curve isn’t integrity,so we enhance the development monitors in the case of close well.Downhole pipe string structure,tool of test pressure and instrument chosing type and the operating processWere introduced.Field test 5 wells in Xifeng Oilfield in 2004, practices show that test technicses in downhole close well can reduce output losing owing to long-term close well,and it’s technologies simple, operating easier,cost lower and have a higheconomic benefit,it also can reduce wellbore storage effect.Test data show radial drainage area and boundary reflection at short time,the precision of well test interpretative on skin factor and formation pressure was increased,it could provide reliable data for oilfield devolopment.