The invention relates to the field of catalytic chemistry, and discloses a solid acid catalyst, a preparation method and application thereof and a method for preparing a furfurals compound. The solid acid catalyst has an amorphous structure, the chemical formula of the solid acid catalyst is AxPyO(4x+ 5y)/2, A stands for IVB group metal element and/or IVA group metal element, and y: x=0.5-4: 1. The method for preparing the solid acid catalyst comprises the following steps: mixing a metal ion source and a phosphorus source in the presence of a solvent; and drying and roasting an obtained solid phase. The molar ratio of the metal ion source to the phosphorus source is 0.5-4: 1. The method for preparing the furfurals compound comprises the following step: carrying out intramolecular dehydration reaction on biomass raw materials in the presence of the solid acid catalyst, a reaction medium and a selectively used accelerant. The invention further discloses application of the solid acid catalyst in catalytic intramolecular dehydration reaction. By the solid catalyst, the biomass raw materials can be effectively catalyzed and converted into the furfurals compound; the solid acid catalyst is environmentally friendly; and conditions are gentle.