The invention discloses a high-efficiency environment-friendly water-free car washing detergent and a preparation method thereof. The high-efficiency environment-friendly water-free car washing detergent comprises sodium polyacrylate, surfactant, sodium stearate, glycol distearate and deionized water. The preparation method includes: adding sodium polyacrylate into the deionized water, stirring at room temperature till complete dissolution, and adjusting pH of the system to obtain first mixed liquid; adding the surfactant into the deionized water, increasing temperature, adding glycol distearate, stirring for dissolving, lowering to room temperature, and adjusting pH of a system to obtain second mixed liquid; adding the second mixed liquid into the first mixed liquid, adding other ingredients, adjusting pH of a system, and stirring and mixing well to obtain the high-efficiency environment-friendly water-free car washing detergent. The high-efficiency environment-friendly water-free car washing detergent is free of any toxic ingredient, free of environment pollution, capable of realizing integration of quick decontaminating, coating and polishing, and supportive of direct use without being diluted by adding water, thereby being water-saving and environment-friendly.