The invention relates to a polyvinyl chloride blending material used for a pressure bearing container, and a preparation method. The preparation method comprises the following steps: (1) starting a high-speed blender mixer at a low speed, adding polyvinyl chloride resin and calcium carbonate into the high-speed blender mixer, carrying out low-speed thermal stirring, evenly stirring; enabling the high-speed blender mixer to carry out high-speed operation, and adding stabilizer, lubricant and toner to be subjected to high-speed thermal stirring; (2) moving materials in the high-speed blender mixer to a low-speed blender mixer under an operation state, carrying out cold stirring, adding stabilizer, lubricant and impact modifier after the temperature of the material in the low-speed blender mixer is stable, and carrying out low-speed cold stirring; (3) sieving blended materials to remove materials of big particles or caked materials; (4) carrying out sealed packaging. The sequence of an auxiliary ingredient adding process is regulated, and the influence of adverse chemical reaction on materials is reduced. The stability of the product is guaranteed, meanwhile, the loss of high-cost auxiliary ingredients is reduced, and cost is lowered.