A large amount of fish processing by-products such as fish skins, fish scales, fish bones, fins and swim bladders are generated along with the development of fish processing industry, and high value utilization of these kinds of by-products has attracted the attention of scientists. Currently, these fish processing by-products are usually made into snack foods, fish meals or collagen products, and due to the higher added-value of collagen products, the extraction of collagen has become a research hotspot. Based on the above background, this work firstly introduced the distribution of collagen in different fish processing by-products, and reviewed the latest developments on the main extraction methods. Furthermore, the extraction rate, purity and physicochemical properties of collagen from different fish processing by-products were also compared and analyzed in this work. Finally, it looked into the prospects and development trends of collagen production using fish by-products as raw materials, proposed that acid swelling-pepsin digestion method was more suitable for fish collagen extraction and had promising prospects especially for fish skin collagen extraction.