As a natural organic polymer with abundant yield, lignin has a large number of active functional groups such as carbonyl, phenolic hydroxyl group, alcohol hydroxyl group and methoxy group in its molecular structure, which provides the possibility for the design and preparation of new functional materials containing lignin. In this paper, the corn straw shell was used as raw material, soaked in alkali solution with pH value of 11 at high temperature, calcium ions (Ca²⁺) were directly added to the lignin extract, and the coordination effect of Ca²⁺ with carbonyl and ether bonds in the molecular structure of lignin was used to prepare micron-scale lignin-Ca²⁺ complex particles. The lignin-Ca²⁺ complex was mixed with an aqueous solution of polyvinyl alcohol (PVA) with a mass concentration of 4%, and PVA/lignin-Ca²⁺ composite plastic films with different complex particle contents were obtained by the solution casting method. The results show that the tensile strength, rigidity, degradation performance, ultraviolet absorption and flame retardancy of PVA film are improved to different degrees after lignin-Ca²⁺ complex particles are added.