The invention discloses a natural detergent and a preparation method and application thereof. The soapberry natural detergent comprises the following components in percentage by weight: 4%-8% soapberry extractives, 2%-5.5% of tea saponin, 1%-2.8% of glycerol, 2%-7.8% of sodium citrate, 1.2%-3.6% of sodium carbonate, 1.5%-3.6% of carboxymethyl cellulose and the balance of water. The soapberry natural detergent disclosed by the invention has the advantages of no stimulation, no toxicity, rapidness and thoroughness in biodegradation, environment protection, sustainable development and the like by adopting the soapberry and the tea saponin as main components; raw materials, namely the soapberry and the tea saponin are convenient and easy to obtain; the soapberry natural detergent is rich and exquisite in foam, has the effects of bacteria growth inhibition, disinfection and the like, achieves a submissive effect by being matched with the glycerol, is regulated in pH value by being matched with the sodium carbonate, further exerts the detersive synergistic effect of the soapberry extractives and the tea saponin, is outstandingly enhanced in detersive capacity and can be widely applied to oil stain washing or fabric washing.