The skin of Acipenser gueldenstaedtii was used as the raw material in this study, and collagens were extracted using acid and pepsin extraction methods. The protein type, structure, thermal denaturation temperature, solubility, and other physicochemical properties of acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were studied and compared with those of bovine achilles tendon type I collagen (BATC). SDS-PAGE patterns revealed that both ASC and PSC contained two typical α chains (α1 chain and α2 chain) and were type I collagens. The Fourier transform infrared spectroscopy (FT-IR) results indicated that both extracted collagens had a triple helical structure, but ASC had a higher degree of molecular order. The denaturation temperatures of ASC and PSC were 32.48 ℃ and 32.68 ℃, respectively, which were lower than that of BATC. Both ASC and PSC had a relatively high solubility at acidic pH (pH 1~4). PSC had a higher solubility when the NaCl concentration was higher than 2%. Scanning electron microscopy (SEM) showed that the two collagen sponges had a network structure, and the pore size of ASC was relatively uniform and small. These results indicate that different extraction methods may lead to certain differences in the physicochemical properties of ASC and PSC; however, both collagens have good thermal stability and solubility, as well as the ability to form a better network structure than BATC. Therefore, the skin from Acipenser gueldenstaedtii can serve as an alternative source of collagens.