The effect of pH value in preparation process on proximate composition, yield and functional properties including gel strength, melting temperature and turbidity of gelatin from bighead carp (Hypophthalmichthys nobilis) scale was investigated. Moreover, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to evaluate the change of molecular weight distribution for fish gelatin. The results indicated that regardless of pH values in the range of 3.0~7.0 for preparation process, fish gelatin had a high quality with high protein content and low ash content. With pH value increasing, the yield of fish gelatin gradually decreased, however, turbidity showed an increased trend. When pH value increased from 3.0 to 7.0, gel strength and melting temperature of fish gelatin increased at first, and then decreased. In addition, gel strength of gelatin from bighead carp scale was related to molecular weight distribution in some extent. Above results in this study could give some technical support in the preparation of fish gelatin with special application.