The invention belongs to the technical field of agricultural and horticultural fertilities and particularly relates to a bovine dung vermicompost seedling culture matrix block and a preparation method thereof. The preparation method includes steps: properly grinding raw materials including wastes of straws, bovine dung vermicompost materials and the like, adding appropriate peat and water-absorbent resin as an expanding agent and a soil sterilizing agent, adjusting, mixing and using a special forming device to realize primary compression and forming to produce the seedling culture matrix block suitable for agricultural and horticultural plants. The invention further discloses corresponding technical steps. Recycling of wastes is realized, and the prepared seedling culture matrix block is rich in nutrition and meets requirements of seedling growth and development of agricultural crops, melons, fruits, vegetables and the like. In addition, environment pollution caused by plastic cave dishes can be reduced while seedling transplantation integration can be realized. The bovine dung vermicompost seedling culture matrix block and the preparation method thereof have the advantages of freeness of root injuries, seedling injuries and a rejuvenation period, high in survival rate and the like.