The thermal insulating plate of composite material is produced with waste foamed phenolic plastic powder as basic heat insulating material, flyash as stuffing, expanded perlite as aggregate, mineral wool, glass wool, sepiolite and palygorskite as reinforcing material, neutral water glass or silica sol as inorganic adhesive and guar gum, methylcellulose or CMC as organic adhesive, and through high speed dispersion, stirring, mixing, molding, forming and drying. The thermal insulating plate has low heat conducting coefficient, is non-inflammable, smell-less, non-toxic, long in service life and wide in application range. The production process adopts industrial waste as main components and produces no waste, and used plate may be reused, so that the present invention is significant in environment protection.