Material recycling of silane cross-linked polyethylene (Si-XLPE) by the solid-state shear milling ((SM)-M-3) technology could produce thermoplastic polyethylene. To take advantage of thermoplastic polyethylene from Si-XLPE, the de-cross-linked mechanism of Si-XLPE in (SM)-M-3 must be evaluated. The products prepared by the (SM)-M-3 technology were characterized using gel content, molecular weight measurement (GPC), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (Si-29-NMR), and re-cross-linking test to obtain insight into the selective de-cross-linking effect of the (SM)-M-3 technology. The results had confirmed that a cross-linking element consisting of Si-O-Si chemical bonds was destroyed during (SM)-M-3, which was responsible for the destruction of cross-linked structures of Si-XLPE materials, and the molecular structures of the resulting products were close to that of silane-grafted polyethylene. The mechanical properties of Si-XLPE materials prepared by the (SM)-M-3 technology before and after water-cross-linking treatment were compared. It was found that the products obtained by the (SM)-M-3 technology could still undergo the cross-linking reaction and form more silane-grafted polyethylene with the increase of milling cycles. Based on the results of this study, we expected that practical applications of de-cross-linking of Si-XLPE materials could be successfully achieved. In this study, favorable conditions were established for the direct recovery of thermoplastic polyethylene from Si-XLPE by the selective de-cross-linking reaction in (SM)-M-3 and an idea about the recycling of Si-XLPE materials was developed.