An integrated blade diffuser design and optimization method is developed for a compact channel diffuser of centrifugal compressors. The hub curve， originally in the form of a “straight-arc-straight” configuration as seen in conventional diffusers， is transformed into a “bulged” shape constructed one using Bezier curves. This modification reduces the curvature of the hub’s turning section， suppressing flow separation at the hub while maintaining a small radial diameter for the diffuser. Additionally， the leading-edge radius is increased to expand the radial clearance between the rotor and stator. The diffuser blades are divided into the front， the middle， and the rear sections for optimization parameter exploration. Four sets of parameters are selected for optimization. Numerical simulations reveal that after optimization， the centrifugal compressor’s pressure ratio at the design points increased by 1.84%， the efficiency is improved by 2.5%， and the surge margin is increased by 8.13%.