The invention discloses a fluorine-gypsum-based machine-spraying thermal insulation mortar and a preparation method thereof and relates to the field of composite thermal insulation material. The fluorine-gypsum-based machine-spraying thermal insulation mortar comprises, by weight, 65-80 parts of fluorine gypsum powder, 4-8 part of quick lime, 3-8 parts of cement, 10-20 parts of superfine slag powder, 0.5-2.5 parts of thixotropic lubricant, 0.7-2.2 parts of EPS particle, 0.4-1 part of redispersible latex powder, 0-0.5 part of water retaining agent, 0.2-0.6 part of starch, 0.5-1.5 parts of gypsum activator, 0.1-0.5 part of polyvinyl alcohol and 35-55 parts of water. The fluorine-gypsum-based machine-spraying thermal insulation mortar is simple to prepare, good in thermal insulation performance, environmentally friendly, energy-saving, applicable to machine spraying and capable of saving cost.