The invention discloses potassium phosphite water soluble fertilizer containing nitrogen, phosphorus and potassium for fruit trees and a production method of the potassium phosphite water soluble fertilizer. The potassium phosphite water soluble fertilizer comprises raw materials as follows: 21-69 parts of phosphorous acid or potassium phosphite, 3.5-6 parts of phosphoric acid or phosphate, 8-41 parts of potassium hydroxide, 6-9 parts of nitrogen fertilizer, 2-30 parts of medium and trace elements, 5-20 parts of complex amino acids, 0.01-0.3 parts of a plant growth regulator. The production method of the potassium phosphite water soluble fertilizer mainly comprises the steps as follows: (1), weighing raw materials; (2), mixing and stirring the raw materials; (3), performing PH neutralization adjustment; (4), adding medium and trace elements; (5), measuring performance; (6), performing freezing; (7), adjusting the product to obtain the potassium phosphite water soluble fertilizer containing nitrogen, phosphorus and potassium for the fruit trees. The product is detected in accordance with the national industry standard of water soluble fertilizer containing nitrogen, phosphorus and potassium NY 1107-2010, the total content of nitrogen, phosphorus and potassium is larger than 500 g/L, and the problems that +3 phosphorus cannot be detected and the total nutrient content of the product cannot reach 500 g/L when previous potassium phosphite aqueous solutions are detected in accordance with the national industry standard of water soluble fertilizer containing nitrogen, phosphorusand potassium NY 1107-2010 are solved.