The invention discloses a biaxial orientation polyvinyl chloride pipe and a preparation formula thereof. The preparation formula comprises 100 parts of PVC (Polyvinyl Chloride), 1.5-3.0 parts of thermal stabilizing agent, 4-6 parts of processing agent, 5-10 parts of toughening agent, 0.2-0.5 part of outer lubricant, 0.3-0.8 part of inner lubricant, 1.0-2.5 parts of titanium dioxide and 0.02-0.04 part of carbon black. The invention further discloses a preparation method of the biaxial orientation polyvinyl chloride pipe. The preparation method comprises the following steps: weighing a raw material, performing a kneading process, performing an extrusion forming process, and performing a stretching and swelling orientation process. Due to adoption of the raw material formulation, by adding a proper amount of the toughening agent, the toughness of a pipe blank to be oriented is greatly improved, no cracks are caused in expansion, and thus the expansion stretching velocity can be increased by multiple times; through inner and outer water bath heating on the pipe blank, the pipe blank is prevented from influence of temperature of an ambient environment in the orientation process, the whole pipe blank to be oriented can meet the orientable temperature, and the time that the pipe is heated to be the expansion temperature is shortened by more than 10%, so that the production efficiency is greatly improved; due to arrangement of an outer diameter fixing sleeve in the expansion procedure, the size precision of the outer diameter and the wall thickness of the pipe is ensured, the pass percent of a product is improved, and the cost is lowered.