6-arm star-shaped Poly (ε-caprolactone)-dextran (sPCL-dextran) was synthesized and characterized. The core of the star polymer is dipentaerythritol, the inner block in the arm is hydrophobic poly (ε-caprolactone) (PCL), and the outer block in the arm is hydrophilic dextran. The synthesis involves three steps: (1) The ring-opening polymerization of ε-caprolactone (CL) initiated by dipentaerythritol produces 6-arm star-shaped PCL (sPCL-OH). (2) The sPCL-OH reacts with acryloyl chloride to get star-shaped PCL with acrylate end group (sPCL-CH=CH2). (3) The amino ended dextran (dextran-NH2) is then attached to sPCL-CH=CH2 terminus by Micheal addition to form star-shaped sPCL-dextran. The architecture of products was characterized with 1H NMR, GPC and element analysis. Micellization of sPCL-dextran in aqueous solutions was investigated by DLS. The results showed that the micelle size (Rh) and size distribution are related to the concentration of the sPCL-dextran. Salt, pH value and temperature have no obvious influence on the Rh.