The invention relates to a hyaluronan and biodegradable high polymer modified material and a preparation method, in particular to a method for complex crosslinking and grafting of the hyaluronan and a derivative thereof with a biodegradable high polymer with active functional groups through a crosslinking agent. The method comprises the steps of taking the hyaluronan and the biodegradable high polymer as raw materials, conducting complex crosslinking or grafting reaction of a hyaluronan aqueous solution and at least one biodegradable high polymer solution with the presence of the crosslinking agent, and removing a solvent. According to the method, plural gel, an amphiphilic polymer, a graft polymer, a star polymer and a microsphere can be prepared. The method has the advantages that the reaction condition is simple, the utilization ratio of the crosslinking agent is high, the residual quantity of the crosslinking agent is small, and the gel is higher in thermostability and good in biological compatibility. The method is applicable to the fields of cosmetics, tissue filling and repair, biological stents, ophthalmonogy, sustained-release delivery and targeted drug delivery and the like, and has a wider application prospect.