As an important component of the hydraulic system of hilly and mountainous tractor，hydraulic integrated blocks can reduce the number of connecting pipes between hydraulic components，and are of great significance in solving the problem of oil leakage caused by oil pipe connections. In this paper，a hydraulic integrated block for attitude adjustment of the suspension system was designed according to the performance requirements of the electro.hydraulic suspension system for hilly and mountainous tractor， the main structural parameters were designed and calculated， meanwhile， a three.dimensional model of the hydraulic integrated block was established. The internal flow channel structure of the hydraulic integrated block was optimized based on the single.objective optimization results of the tool tip angle，process holes，and non.orthogonal channel，the response surface analysis of the combined flow channel，the CFD analysis of the overall flow channel，and the fluid.solid coupling analysis. Finally，the CFD simulation and fluid.solid coupling simulation are used to compare the performance before and after optimization. The simulation results showed that：after optimization， the pressure loss of the inlet and return channels of the lateral attitude adjustment of the oil supply to port A is reduced by 0. 005 MPa and 0. 013 MPa，respectively，compared with that before optimization. The pressure loss of the inlet and return channels of the lateral attitude adjustment of the oil supply to port B is reduced by 0. 048 MPa and 0. 015 MPa，respectively. The pressure losses in the inlet and return channels of the lifting circuit decreased by 0. 129 MPa and 0. 003 MPa，respectively，which verified the superiority of optimized hydraulic integrated block.

"> hilly and mountainous areas, tractors, electro.hydraulic suspension system, hydraulic manifold block, CFD , simulation, structural optimization ,