The invention discloses a crosslinked 
polyethylene cable insulating material with a water treeing resisting function and a preparation method of the material. The crosslinked 
polyethylene cable insulating material is prepared from the following components in parts by weight: 80-97 parts of low-density 
polyethylene, 3-20 parts of a water treeing resisting modifier, 1-2 parts of a crosslinking agent, 0-0.5 part of a crosslinking assistant, 0.2-0.8 part of an 
antioxidant and 0-0.5 part of a 
rheology modifier. The water treeing resisting modifier is prepared from nano 
silicate, a surface modifier, a polymeric compatibilizer and polyethylene. Compared with the prior art, the crosslinked polyethylene cable insulating material has the characteristics that the polyethylene, the polymeric compatibilizer and the nano 
silicate are melted and blended to obtain an intercalated 
composite material; successful intercalation of the polyethylene between nano 
silicate layers is ensured by an organic surface treatment agent; carbonyl on a compatibilizer molecule chain is combined with hydroxyl between the silicate 
layers by a 
hydrogen bond, and then entangled with a 
polymer matrix molecule chain, so that the interfacial interaction between the 
polymer and layered silicate is improved, and the 
composite material has excellent water-resistant tree performance due to the barrier property of the nano silicate 
layers.