Abstract: Compressor endwall treatments,such as grooves and slots can effectively delay stall and increase the weight flow range of a compressor,but the efficiency decreases.A new kind of casing treatment,called as sloped slotted casing treatment,has been designed,which absorbs the advantages of traditional casing treatments.The overall performance of compressor rotor with sloped slotted casing treatment is measured at a single axial flow compressor.The effects of the axial overlapping amount and back cavity volume on stall margin and efficiency have been found.In each case,its characteristics with the casing treatment are compared to those without it.The results show that the new kind of casing treatment can effectively increase the stall margin and efficiency.Both flow suction and injection from the treatment region makes a stall margin improvement.