In this paper, the reaction process parameters of the hydrogel produced by the modified gelatin from chicken, bovine and porcine lungs with carboxymethyl chitosan (CMCS) and oxidized glucomannan (OKGM) were optimized to produce Schiff base reaction. The results showed the properties of the three composite hydrogels are improved when the value of gelatin/CMCS/OKGM reached 1:2:2. The best modified gelatin/CMCS/OKGM of bovine lung composite hydrogel (COBH) had a gelatin strength of 8.14 N, a swelling rate of 257%, a water evaporation rate of 66.86%, and an antibacterial property of 38.02%. The properties of modified gelatin/CMCS/OKGM of chicken lung composite hydrogel (COCH) were similar to those of COBH. However, the water holding capacity of COCH was higher than that of COBH. The properties of the modified gelatin/CMCS/OKGM for porcine lung composite hydrogel (COPH) were significantly decreased over those of the other two. Therefore, COCH has potential applications in food coating and preservation.