The invention discloses a graphene oxide modified cement-based composite heat-insulating material and a preparation method and application thereof, and belongs to the field of building materials. Theheat-insulating material is prepared from the following raw materials in parts by weight: 40-60 parts of cement, 10-30 parts of coal ash, 5-10 parts of silica fume, 5-10 parts of quick lime, 0.1-0.5 part of graphene oxide, 0.2-0.7 part of zinc oxide whisker, 1-5 parts of physical foaming agent, 1-4 parts of water reducing agent, 0.2-1 part of dispersing agent, 7-20 parts of polystyrene particles,and 1-6 parts of hydroxypropyl methyl cellulose. The heat-insulating material is capable of using the cement and the coal ash as principal raw materials, through the synergistic effect of the grapheneoxide and the zinc oxide whisker, modifying the properties of foam concrete, introducing the nano-scale graphene oxide and the zinc oxide whisker into a traditional concrete technology by using a physical foaming method, and under the synergistic effect of multiple substances, enabling the heat-insulating material to have multiple functions of light weight, low heat conductivity coefficient, highcompressive strength and the like.