The present invention is related to a composition of PI3K inhibitor, comprising: 0.01˜10 mg of PI3K inhibitor 10˜500 mg of poly(lactic-co-glycolic acid) (PLGA) which is encapsulated onto the surface of the PI3K inhibitor and the surface is non-modified by a modifier and the composition has a size of 10˜1000 nm. Thereby, an excellent effect on suppressing the growth of tumor cells will be achieved by the encapsulation of PI3K inhibitor into PLGA nanomaterials without any modifier on its surface, the optimization of a ratio of PI3K inhibitor to PLGA, and the accordingly slow release of the composition.
