The invention relates to low-carbon ceramic wall body heat insulating paste and a preparation method thereof. The heat insulating paste comprises the following components in percentage by weight: 5 to 30 percent of inorganic binder, 3 to 10 percent of film former, 10 to 50 percent of perlite, 5 to 20 percent of cenospheres, 5 to 10 percent of inorganic filler, 1 to 1.2 percent of fiber, 1 to 1.2 percent of additive and 10 to 50 percent of water, and the total weight percentage of the components is 100 percent. The heat insulating paste has the advantages of low carbon, environmental protection, low smoke, no toxicity, compliance with green architecture energy-saving standards, small volume weight, excellent heat insulating performance and excellent mechanical properties, can be well bonded with the building wall and the veneer thereof, can realize firm binding effect with the wall only through an application process, and solves the problem that the veneer surface of commonly used organic heat insulating material is easy to have quality problems, such as surface layer mortar cracking, fall-off and hollowing. Simultaneously, the invention has the advantages of simple and convenient construction, makes up for the defects of complicated construction and long construction time of foam heat insulating material, has excellent anti-cracking, water resistant and aging resistant performance, and solves the problems of commonly used silicate heat insulating material cracks during a curing process and has low water resistant performance. The masonry structures of the material do not produce any gap, so that the heat loss rate is further reduced and the cost is low. The invention has simple process, greatly reduces manpower and materials, simultaneously selects perlite, ceramic beads and other inorganic materials with rich sources, greatly reduces the economic cost and has quite good advantages in the heat insulating material industry.