Sheep liver is a by-product of lamb or mutton production, which is rich in various nutrients and has high research value. However, the fishy smell of sheep liver, which is difficult to remove, restricts its further processing and utilization. To promote the development and utilization of this by-product, lamb liver was used as a raw material to produce lamb liver powder, which was characterized through sensory evaluation, as an indicator, and the removal of the fishy smell of lamb liver powder was assessed. Six factors were evaluated using single-factor experiments: the rinsing frequency, rinsing time, cooking time, concentration of additives, drying time, and drying temperature. Based on the single-factor experiment, the Box Behnken response surface design method was used to optimize the process for removing the fishy smell from sheep liver powder. Secondly, gas chromatography-ion mobility spectroscopy (GC-IMS) was used to analyze the optimal deodorization process and the volatile substances in sheep liver that had not been deodorized, to determine the effectiveness of the treatment process. The sensory score for removing the fishy smell from sheep liver powder was the highest when the process was conducted by rinsing at 40 ℃, rinsing 5 times, adding 4% (m/m) excipient, cooking for 50 min, and drying for four hours at 65 ℃. The GC-IMS results indicate that through the optimal deodorization process, various undesirable flavors and a large number of volatile aroma compounds such as aldehydes, ketones, and alcohols can be removed. The deodorization effect is significant, and the flavor improvement is good. The results provide a theoretical basis and reference parameters for optimizing the deodorization of lamb and its by-products.