Triblock copolymers from poly(ethylene glycol) (PEG) and D,L-lactide or epsilon-caprolactone were synthesized to prepare semi-interpenetrating polymer networks (semi-IPNs) with chitosan by ultraviolet (UV) irradiation method. Then, the solute permeation through these semi-IPNs hydrogels were investigated. The structures of semi-IPNs were confirmed by Fourier transform infrared (FTIR) spectroscopy and wide-angle X-ray diffractometer (WAXD). The equilibrium water content (EWC) of these hydrogels was in the range of 67-75%. The crystallinity, thermal properties, and mechanical properties of semi-IPNs hydrogels were studied. All the hydrogels revealed a remarkable decrease in crystallinity as compared with the PEG macromer itself. The tensile strengths of semi-IPNs hydrogels in a dry state were rather high, but those of hydrogels in a wet state decreased drastically. The permeabilities of solutes of hydrogels followed the swelling behaviors and were regulated by solute size.