The invention discloses a one-step method silane crosslinking polyethylene insulating material, which is prepared from polyolefin, an initiating agent, a silane coupling agent, a catalyst, a lubricating agent, an antioxidant and an anti-pre-crosslinking agent. Various kinds of resin are used in a formula system for compounding; the anti-pre-crosslinking agent is added; when the material melt grafting temperature is reduced; the pre-crosslinking cannot be easily generated; the heat shrinkage performance of a finished product is also improved; at the same time, a nitrogen gas pressure retaining fast absorption infiltration method is adopted for preparation. Compared with a traditional preparation process and a formula, the preparation method has the advantages that materials can fast be dispersed and uniformly wrap particle surfaces, and are fast infiltrated inside particles; the process step is simplified (the labor hour is short); the energy consumption is reduced; the labor force is reduced; the flowability is good; the extruded surface is bright; the performance is excellent; the product is stable. The method is used for producing the silane crosslinking polyethylene insulating material.