The effects of applied pressure, holding time, protein concentration, CaCl2 and pH on properties of whey protein isolated (WPI) gel processed by ultra-high pressure (UHP) were investigated. Only treated by UHP on the condition of applied pressure≥300 MPa, holding time ≥10 min and protein concentration ≥120 g/L, would WPI pressure-induced gel be formed. And the disulfide bond was increased with time, pressure and WPI concentration. These conditions provide gels with finer structure, higher strength and yield and better water-holding capacity. Above the isoelectric point, especial for neutral environment, pressure-induced WPI gels had better gel properties, higher disulfide bond and finer structure. The CaCl2 had no changes on disulfide bond content, but can increase the gel strength by the bridge bond. Yield had negative correlation with CaCl2 concentrations. When the concentration of CaCl2 was 0.06 mol/L, water-holding capacity of WPI gel had a maximum value, but it will decrease with higher concentration of CaCl2.