Abstract: A set of tandem blades with BC 6 profile has been designed and manufactured for a development program to modify an aeroengine.In order to demonstrate the advantages of the tandem blades,the tests have been conducted in cascade wind tunnel,at compressor test stand and on engine bed,respectively.The cascade test data show that the total pressure loss coefficient for the tandem blades is 0 0305,but it is 0 0348 for the single row of blades at the same design conditions.The range of efficient incidence angle for the tandem blades is 31 2% larger than for single row blades.As compared with the compressor of the single row blades,the tandem blades compressor test results indicate that its adiabatic efficiency is enhanced 1 3% and its surge margin is enlarged 2 8% at the design speed and the design pressure ratio.The engine tests also prove that the operation line of the aeroengine with the set of tandem blades is farther from the compressor stall line.The paper describes how to select the tandem blad parameters and how to obtain the optimum axial and tangential distances between the two rows of this tandem cascade from the test data.The paper also considers the feasibility of the tandem blades in the aeroengine to expand its range of stable operation.