In order to prepare 3D skeletal polymer with low cross-linking density and high hydrophilicity bisphenol A epoxy was cured with diethylenetriamine in the PEG1000/PEG2000 mixing medium. The reaction-induced phase separation of this system was controlled by changing the weight ratio of PEG1000 and PEG2000. The morphology observation of the resulted polymers showed that the connectivity of epoxy phase strongly depended on the content of PEG2000 and was also influenced by the curing temperature. A 3D skeletal polymer with well-controlled macro-through-pores was prepared by using a mixture of PEG1000 and PEG2000 in 7/1 weight ratio as reaction medium and porogen. A unique light-filtrating effect was found in the prepared 3D skeletal polymer that filled with high refractive liquids. The effect most likely resulted from a total reflection mechanism of light in 3D macro-through-pores.