Objective: The evaluation of intraocular pressure (IOP) after vitreoretinal surgery is critical to ensure the normal function of the eye. The purpose of this study was to determine the incidences and risk factors of early postoperative IOP elevation after vitreoretinal surgery. Method: Data were collected and retrospectively analyzed from 150 patients (150 eyes) who received vitreoretinal surgery from March 2012 to December 2012 in Tongji Hospital. IOP was measured before surgery and on day 1, 2, 3, 4-7 after surgery by Goldmann applanation tonometer. Ocular hypertension was defined as IOP ≥ 24 mmHg. The incidences and risk factors were analyzed. Results: 87 of the 150 patients were male and 63 were female. The IOP was elevated significantly in 54 eyes (36.00%) within 1 week after vitreoretinal surgery. Among them, 31 eyes (57.40%) occurred on day 1; 14 eyes (25.93%) occurred on day 2. The incidences of elevated IOP between different primary diseases had no statistical difference (p>0.05). However, patients with proliferative diabetic retinopathy (PDR), and rhegmatogenous retinal detachment (RRD) with proliferative vitreoretinopathy (PVR) grade ≥ C2, had higher rates of IOP elevation. Vitrectomy combined with cataract surgery or scleral buckling had no significant difference in IOP elevation compared with vitrectomy only (p>0.05). The rate of IOP elevation between 20G pars-plana vitrectomy (41.76%) and 23G pars-plana vitrectomy (27.40%) had statistical difference (p=0.033). The incidence of IOP elevation with intraocular tamponade of C3F8 was significantly higher than simple vitrectomy (chi2=7.723, p=0.005), while with silicone oil, the difference was not significant (chi2=3.627, p>0.05). Conclusion: IOP measurement after vitreoretinal surgery is important to monitor and prevent unintentional high IOP as it is a common complication after vitreoretinal surgery. The risk factors of early IOP elevation include the 20G pars-plana vitrectomy and C3F8 injection. Early treatment of IOP may prevent IOP spike to protect the vison.