An optimization method of intake system combining the advantages of describing 3D flow characteristics of intake system accurately and 1D global control was put forward based on 1D and 3D coupling simulation. The 3D model of intake manifold was established, the incylinder working process was simulated with GTPower software and the simulation model was finally calibrated according to the test data. The flow parameters of intake manifold at each speed were acquired by 1D and 3D
coupling simulation and then the structural parameters of intake manifold were optimized by taking the acquired parameters as boundary condition of CFD
simulation. The flow performance of intake manifold was verified by engine test. The experimental results show that the method can guide the design of intake manifold well.