HSulf-1 (heparan sulfate 6-O-endosulfatase 1), a commonly downregulated gene in the majority of ovarian cancer cell lines, has been identified to play an important role in regulating tumorigenesis. Our previous studies demonstrated that HSulf-1 could inhibit angiogenesis and tumorigenesis in vivo. The employment of polymeric nanoparticles to deliver functional gene holds much promise as an effective therapeutic strategy against ovarian cancer. To develop more effective therapy, in this study, we investigated the antitumor effect of heparin-polyethyleneimine (HPEI) nanogels delivering HSulf-1 combined with cisplatin (DDP) on ovarian cancer. Expression of HSulf-1 in vitro and in vivo was determined by reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis. A SKOV3 intraperitoneal ovarian carcinomatosis model in nude mice was established to assess the antitumor efficacy. Mice were treated with NS, pEP/HPEI complexes, pHSulf-1/HPEI complexes, DDP or pHSulf-1/HPEI plus DDP, respectively. Intraperitoneal tumors were weighed. Antiangiogenic effect in vivo was evaluated by CD31 immunostaining and alginate-encapsulate tumor cell assay. Detection of the proliferative cells and apoptotic cells in tumor tissues were performed by Ki-67 staining and TUNEL assay. Stable expression of HSulf-1 was detected in the pHSulf-1/HPEI and pHSulf-1/HPEI plus DDP groups. The combination of pHSulf-1/HPEI complexes with DDP exhibited enhanced antitumor activity, compared with the monotherapy of HSulf-1 or DDP alone (P<0.01). the combination therapy exerted significant antitumor activity through enhanced antiangiogenesis, induction of apoptosis and suppression of cell proliferation. Collectively, these observations provide evidence that HPEI nanogels delivering HSulf-1 combined with DDP may have a promising application in the therapy of human ovarian cancer.