By using a combined method of density functional theory(DFT), molecular mechanics(MM2) and statistics for two-dimensional(2D), as well as the comparative molecular field analysis(Co MFA) and comparative molecular similarity index analysis(Co MSIA) methods for three-dimensional(3D), theoretical studies on 2D/3D quantitative structure-activity relationships(QSAR) of 22 novel compounds of [1,2,4]triazolo[1,5-a] pyridinylpyridines acting as PI3 K inhibitors against the human colon carcinoma cell line(HCT-116) have been performed. Both the 2D- and 3D-QSAR models established from the random 18 compounds in training set show significant statistical quality and satisfactory predictive ability(R2 = 0.821, q2 = 0.773 for 2D-QSAR, R2 = 0.966, q2 = 0.668 for Co MFA, R2 = 0.979, q2 = 0.753 for Co MSIA). The combined 2D- and 3D-QSAR studies suggest that the moderate-size, hydrophilic and electron-withdrawing group at R1 position, the bulky and hydrophobic group at R2 position, and the minor, hydrophobic, H-bond donor and electron-donating group at R3 position would enhance the anticancer activities. These obtained results help to insight into the action mechanism, and will serve as a basis for the design of new potent anticancer agents.