The invention relates to a soilless culture medium used for flowers and ornamental plants. The soilless culture medium is prepared by performing activation and nutrient solution treatment on natural zeolite gravel and controlling the pH value and the concentration so as to meet different requirements of different varieties of flowers on water, fertilizer and the pH value. Phosphate ore, perlite, vermiculite and the like serve as additional ingredients to be added into the zeolite gravel, and the product can be adjusted in multiple aspects to achieve the best effect. Due to good properties of water absorption and retention, fertilizer absorption and retention and air permeability, growth of multiple varieties of flowers is promoted, neither soil or organic matter exists, disinfection can be conducted, and potted flowers are clean and free of toxin, odor and germ. A color gravel covering layer enhances the ornamental effect, and the soilless culture medium can be widely used for soilless culture of indoor ornamental flowers in various occasions.