Abstract: According to a lot of duct stable flow test results,the straight and helix intake ducts were specially designed and properly set for the variable swirl system in this paper to achieve the best effect for swirl regulating.The controllable intake swirl system could work at two modes.The system was controlled by PC in one mode or controlled by ECU in the other.The performance of 1132Z single-cylinder diesel engine with controllable intake swirl system at different working conditions was studied on the test bench.The test results indicate that the specific fuel consumption and the smoke is both reduced with variable intake swirl,specially at low speed condition.