A chip package structure is provided. The chip package structure includes a substrate. The chip package structure also includes a first chip structure and a second chip structure over the substrate. The chip package structure further includes an anti-warpage bar between the first chip structure and the second chip structure. In addition, the chip package structure includes an underfill layer between the first chip structure and the second chip structure and between the anti-warpage bar and the substrate. A topmost surface of the underfill layer is lower than a top surface of the anti-warpage bar.