The aim of the experiment was to investigate the effects of wet extrusion on the content of nutrients and free gossypol in cotton meal (CM) and explore the effects of extruded cotton meal (ECM) on growth performance, serum biochemical indices and nutrient apparent digestibility of growing-finishing pigs. Firstly, Muyang 56×2 expanding machine and the early optimized processing parameters were used to expand the CM, and the content changes of nutrients and free gossypol in CM and ECM were measured. Then, CM and ECM were used as the main experiment materials, and eighty pigs (Duroc×Landrace×Large White) with the body weight of (28.78±3.09) kg were randomly allocated to 5 groups with 4 replicates each and 4 pigs in each replicate (half male and half female). Pigs in control group were fed an all corn-soybean meal basal diet, in experimental group 1 were fed the basal diet supplemented with 5% CM to growing pigs and 10% CM to finishing pigs, and in experimental groups 2, 3 and 4 were fed the basal diets supplemented with 5%, 10% and 15% ECM to growing pigs and 10%, 15% and 20% ECM to finishing pigs, respectively. The metabolic energy, crude protein content and other nutrition levels in all diets were balanced. The experiment lasted for 13 weeks with 6 weeks of growing period and 7 weeks of finishing period. The results showed as follows:1) extrusion on CM had no obvious effects on nutrient content, and the contents of total amino acids and essential amino acids in ECM were increased slightly, while the free gossypol content in ECM was decreased by 87.85%. 2) In the growing stage, compared to 5% CM, dietary 5% ECM increased the average daily feed intake and average daily gain of pigs (P>0.05), significantly decreased the ratio of feed to gain (P<0.05), and significantly increased the apparent digestibility of crude protein, dry matter, ether extract and some amino acids (P<0.05). Compared with CM, the serum malondialdehyde (MDA) content was significantly reduced, and the serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity, glutathione peroxidase (GSH-Px) activity were significantly improved after the pigs were fed the diets supplemented with ECM (P<0.05). The serum contents of immunoglobulin, triiodothyronine and tetraiodothyronine tended to be enhanced of growing pigs by feeding the ECM compared with CM. With the addition of ECM increasing, the growth performance and nutrient apparent digestibility of the growing pigs showed a decreasing trend, and there was no significant difference between 15% ECM group and common CM group (P>0.05). 3) During the finishing stage, there were no significant differences in the final average body weight, average daily weight gain and average daily intake from the ECM groups to the control group and common CM group (P>0.05). However, the feed to gain ratio in experimental groups 1 and 3 was significantly lower than that in experimental group 1 during the whole stage (P<0.05). It can also significantly improve the antioxidant capacity and immunity of finishing pigs fed the ECM compared with the CM, and with the addition of ECM increasing, the serum MDA content of finishing pig was significantly decreased (P<0.05), and the serum T-AOC, activities of SOD and GSH-Px were increased gradually (P<0.05). Compare with the control group, the apparent digestibility of crude protein and dry matter was significantly lower than that in experimental groups (P<0.05). The crude protein apparent digestibility in ECM groups was not significant different compared with experimental group 1 (P>0.05). The dry matter apparent digestibility in ECM groups was significantly higher than that in experimental group 1 (P<0.05). The ether extract apparent digestibility in experimental groups 3 and 4 was significantly higher than that in the control group and experimental group 1 (P<0.05). With the addition of ECM increasing, the ether extract apparent digestibility was increased gradually. The addition of a moderate amount of ECM can significantly improve the apparent digestibility of amino acids compared with CM (P<0.05). Thus, the effects of extruded puffing on the nutrient contents of CM is not obvious, but can significantly increase the free gossypol content in CM. Dietary ECM can improve the growth performance, antioxidant capacity, immune capacity and nutrient apparent digestibility of growing-finishing pigs, and it is suggested that the amount of ECM for the growing pig is about 15%, and for finishing pig is about 20%.