The invention provides a vermiculite-based composite phase change heat storage material and a preparation method thereof. The material is composed of the following components in parts by mass: 15-38 parts of expanded vermiculite, 50-72 parts of phase change materials and 10-15 parts of graphite. The preparation method comprises the following steps: respectively drying and grinding the raw materials, mixing with 2-5 parts of water, homogenizing, molding, drying and sintering. The heat storage material prepared by the invention has a stereotype structure of different shapes (figure 1), has the heat storage density of more than 400kJ/kg (figure 2) and thermal conductivity of more than 1/(m.K) and is wide in application temperature range, low in corrosion, safe, reliable, low in cost and long in service life. The vermiculite-based composite phase change heat storage material can be applied to the fields of solar energy and wind power generation heat storage and exchange systems, industrial waste-heat utilization and movable heat storage vehicles or movable heat storage stations, and the like.