Abstract: There are many problems such as long production period and serious pollution issued from acid and alkali existing in the production process of gelatin by traditional acid or/and alkali-base pretreatment method. The new pretreatment method using the ultra-high pressure (UHP) technology was investigated in this study to improve the traditional production process of gelatin and establish a clean and efficient preparation method. The effects of UHP pretreatment to the yield and gel strength of gelatin from pig-skin using different transmitting media were studied by comparison with controls treated by non-pretreatment and acid. The optimal UHP pretreatment method was selected and some factors such as pressure, time of UHP and concentration of acid were optimized further for the gelatin extraction. The results show that UHP pretreatment can improve the extraction yield and gel strength of gelatin. The best effect was got by combined pretreatment with UHP and acid. The optimal conditions were that UHP level was 250 MPa, UHP time was 10 min and HCl concentration was 0.75%, under which condition the extraction yield and gel strength of gelatin were up to 88.62% and 384.43 g, respectively. The SDS-PAGE patterns show that the UHP-treated gelatin contains higher mass fraction of high molecular components, such as two different α chains, β and γ-components, compared with that in gelatin treated by traditional method, which is possibly the reason for the high gel strength in UHP-treated gelatin. The results of the study can provide a technical reference for UHP technology application and establishment of clean production process in gelatin preparation.