The invention discloses a preparation method of grapefruit and green tea effervescent tablets. Every 2000 tablets contain ingredients of 400-500g of green tea concentrated powder, 90-110g of grapefruit powder, 15-18g of vitamin C, 2200-2400g of anhydrous citric acid, 1700-1850g of sodium bicarbonate, 1500-1650g of lactose, 700-1300g of sorbitol and the like. The preparation method comprises the technological steps of performing weighing, performing screening, performing premixing, preparing soft materials, performing wet granulation, performing drying and total mixing, performing tabletting, performing detection and the like to obtain finished products. Each tablet contains 100mg of instant green tea and greater than or equal to 20mg of tea polyphenols, and besides, beneficial components of the grapefruits and the green tea are combined. The grapefruit and green tea effervescent tablets can achieve the purposes of being nutritive, being health-care, removing summer-heat, quenching thirst and refreshing oneself; the effervescent tablets are designed, so that the grapefruit and green tea effervescent tablets are convenient to carry; and the products have the characteristics of beingfragrant and sweet in taste and mild in color.