The invention discloses an acid modified palygorskite-polyurethane porous material as well as a preparation method and an application thereof, belonging to the technical field of synthesis of inorganic-organic materials. According to the preparation method of the acid modified palygorskite-polyurethane porous material, palygorskite is modified for preparing acid modified palygorskite, polybasic alcohol, foaming agent, a foaming stabilizer, water and a catalyst are added, mixed and uniformly stirred, then diisocyanate is added for mixing and foaming at a temperature of 50-70 DEG C, and finally the mixture is subjected to aging at the temperature of 90-105 DEG C for 1-2 hours, and after being cooled, the acid modified palygorskite-polyurethane porous material is obtained. Aiming to the characteristics of rich reserves, low cost, non-abrasion property, high chemical stability, large specific surface area and the like of palygorskite, the preparation method of acid modified palygorskite-polyurethane porous material via foaming by one step is provided. Additionally, by the adoption of the prepared acid modified palygorskite-polyurethane porous material in the absorption of cationic dye, the operation is simple, the cost is low, the absorption rate is high, and the use value is higher.