The invention discloses a high-thermal conductivity composite hydrated salt phase-change heat storage material and a preparation method thereof. The high-thermal conductivity composite hydrated salt phase-change heat storage material comprises the following raw materials in percentage by weight: 60-75 percent of hydrated salt, 0.5-5 percent of an additive, 10-20 percent of an adsorbent and 10-30 percent of a heat conduction agent. The preparation method comprises the following steps: during preparation, weighing the hydrated salt and the additive according to the formula ratio to uniformly stir, then adding the adsorbent, uniformly mixing through a pulverizing machine, then sealing and putting in a blast oven to heat till complete fusion; and pulverizing with the pulverizing machine afterfooling, adding the heat conduction agent to uniformly stir and press-molding. The high-thermal conductivity composite hydrated salt phase-change heat storage material and the preparation method thereof disclosed by the invention has the benefits that by selecting the proper ratios of the adsorbent and the heat conduction agent, the cycle stability and the thermal conductivity of the composite material are effectively enhanced; after 100 cycles, the heat storage performance of the material is almost attenuated, and the heat conduction rate can reach above 9 W/m.K.