A package substrate is disclosed. The package substrate includes a molding layer, a redistribution structure, and a build-up structure. The redistribution structure is embedded in the molding layer with a surface exposed by the molding layer. The build-up structure is formed on the bottom surface of the molding layer. An inner stress caused by a CTE difference between different materials in the package substrate is reduced by forming at least one groove which is arranged around the periphery of the redistribution structure onto the top surface of the molding layer, thereby improving the problem of the redistribution structure cracking in the prior art.