The invention discloses a preparation method of crosslinkable polyethylene cable material, which includes the steps and the following components are represented in proportion by weight: throwing polyethylene 75-95 proportion by weight, ethylene-vinyl acetate copolymer 0-20 proportion by weight, unsaturated silicone hydride 1.0-5 proportion by weight, free radical evocating agent 0.1-0.5 proportion by weight, organotin catalyst 0.1-1 proportion by weight, organic acid compound 0.1-1 proportion by weight, anti-oxidant 0.1-0.5 proportion by weight, anti-copper agent 0.1-0.5 proportion by weight, and lubricant 0.5-2 proportion by weight into the high speed mixing machine with rotary speed at 80-120 rpm for mixing 15-25 minutes, and then adding the mixture into the double-screw extruder, melting and prilling for obtaining crosslinkable polyethylene cable material. The method provided by the invention mixes all the material and dispersing uniformly, and then executes grafting reaction, thereby realizing more uniform grafting reaction and guaranteeing homogeneity of the crosslinking process, in addition, the invention uses organic acid compound which remarkably improves catalysis function of organotin catalyst, and improves crosslinking speed of silicone hydride, and overcomes the defect that the conventional silicone hydride crosslinked plastic can be linked only in warm water or steam environment with long time cooking, thereby saving production cost for manufacturer considerably. The crosslinkable polyethylene cable material obtained according to the invention is extruded by plastic cable extrusion machine unit for obtaining cable insulation layer, and is placed under the condition of 23 DEG C. with 50% humidity for one day naturally, then the crosslinking process is finished, moreover the product can pass performance indexes of hot extension performance test, dynamics test and aging characteristic test according to the national standard request.