The invention relates to a dendritic polymer with POSS group and preparation method thereof. The preparation of the product comprises the following steps: designing a POSS group intermediate R2-POSS-(R1)n-1 (n=6, 8, 10, 12) with asymmetric structure, and then using a chemical synthetic method, and obtaining a dendritic polymer (containing derivatives thereof) containing POSS group and a lot of end functional groups. The product has the advantages of unique structure design and diversified selections, thereby the product has latent application prospects for the aspects of surfactant, biological medicine carrier, catalyst, photon crystallization, optical material, anti-corrosion material, electronic material, information recording material, printing material, battery material, magnetic material, electronic luminescent device, etc.