Abstract: A series of poly(4-methyl-ε-caprolactone)s (PMCLs) with four-arm topological structures were prepared by ring opening polymerization(ROP) using pentaerythritol (PE) as the initiator and 4-methyl-ε-caprolactone (MeCL) as the monomer.Photocurable prepolymers were synthesized by attaching acryloyl chloride to the ends of PMCLs.Crosslinking of prepolymers was carried out in the presence of photoinitiator under UV light.The structure and rheological properties of the prepolymers were tested by ¹H-NMR,GPC and the rotational rheometer.Results showed that the PMCLs were synthesized successfully,and the polymerization was controllable and rheological properties were adjustable.The modulus reduced but the elongation at break increased with the increasing of the arm length of PMCL prepolymers.