Abstract: Phosphatidylinositol-3-kinase (PI3K) inhibitors can increase the sensitivity of tumor cells to Poly ADP-ribose polymerase-1 (PARP-1) inhibitors. Therefore, the simultaneous inhibition of the PARP-1 and PI3K activities are expected to overcome the drug resistance of PARP-1 inhibitors.In our previous work, two compounds XW-1 and WZ-1 with excellent activities against PARP-1 and PI3K were obtained with the limitation to further study due to their poor water solubility.Therefore, XW-1 and WZ-1 were chosen as lead compounds to optimize their solubility by introducing a salt-forming site via a urea group, and 11 novel compounds were designed and synthesized. The structure of all target compounds was confirmed by ¹H NMR, ¹³C NMR, and HRMS.The enzyme activities of the compounds against PARP-1 and PI3K were measured, and the results showed that most of the compounds demonstrated good inhibitory activities against PARP-1 and PI3K.Based on the above result, the inhibitory activities of compounds 8b, 8e, and 8f against MDA-MB-231, MDA-MB-468, HCC1937, HCT116, and olaparib-resistant HCT116R were determined by MTT, respectively.Additionally, the structure-activity relationship was discussed. The results showed that these compounds displayed excellent antiproliferation activity.Among them, compound 8f demonstrated antiproliferation remarkably against all five tumor cells, which was more potent than that of olaparib, and was comparable to that of BKM120.Furthermore, the solubility of hydrochloride salts of compound 8b and 8f was significantly improved compared to the lead compounds.The results of this study will provide a theoretical basis for the further development of PARP-1 and PI3K dual-target inhibitors with good pharmaceutical properties and strong inhibitory activities.