The invention provides a drying-free preparing technology adopting a particle boric magnesium fertilizer acid method. The drying-free preparing technology comprises the following steps that 1, wet boric sludge is thrown into a double-shaft mixing machine, 92.5% concentrated sulfuric acid is added to enable boron and magnesium in the boric sludge to be acidified and decomposed, heat is emitted, carbon dioxide and water vapor escape, the temperature for materials is 65 DEGC-80 DEG C at the moment, a pH value is 7-8, and a part of magnesium oxide forms magnesium sulfate monohydrate; 2, after being stirred, magnesium sulfate monohydrate is cooled and stands, and after the water escapes completely, the boric sludge begins hardening and is naturally dried into blocks, namely acidified boric sludge blocks; 3, the acidified boric sludge blocks are smashed to obtain dry powder; 4, the smashed dry powder is pelletized in an acid spraying mode in a disc palletizing machine with 40-68% dilute sulfuric acid serving as an adhesion agent, the boric sludge is further acidified and prepared into balls, and the balls are cooled and screened to obtain finished products. By the adoption of the drying-free technology, consumption of fire coal is omitted, and production cost is effectively reduced; meanwhile, the boric sludge serves as a basic material, drying is avoided in the acid method, and harm to the environment from the boric sludge can be reduced effectively.