Abstract: Hydrogel was one of main materials for medical dressings due to the excellent performance such as high elasticity, high water content, cold effect, strong moisture retentiveness and variable shape. Collagen (COL) had good biocompatibility and can promote cell proliferation. And Sodium humate (NaHA) possessed hemostatic, anti-inflammatory and other biological functions. Therefore, a novel collagen-sodium humate composite hydrogel was prepared by mixing collagen and NaHA at various COL∶NaHA ratios and collagen self-assembly, which was expected to be applied as medical dressing. Then the interaction between collagen and NaHA and the microstructures and properties of composite hydrogels were investigated. The collagen triple helix is not affected, although hydrogen bonds and electrostatic interaction occur between collagen and NaHA. At COL∶NaHA≤4∶6, the hydrogels possess good compatibility due to the shielding effect of NaCl on electrostatic binding; however, the coagulation takes place with the further increase in NaHA content. At COL∶NaHA=4∶6, the percentage of NaHA incorporated into collagen fibrils is highest and 93.2%, and the compatibility between collagen and NaHA is good; therefore, the properties of composite hydrogel consisting of mature fibrils with D-periodicity are optimum. Moreover, about 80% of NaHA still remain in hydrogel, indicating its release is slow. The thermal stability improves by 34.9°C, and storge modulus and loss modulus are 31.89 Pa and 3.99 Pa, respectively. Furthermore, the pore sizes of the lyophilized composite hydrogels decrease and the pores become dense and well-distributed. The composite films have significant rises in hydrophilicity.