The invention discloses a citric acid loofah sponge preparation method and an application technology. The preparation method provided by the invention is characterized by comprising the following steps of: adding 18-25 wt% of citric acid, 18-25 wt% of saponified loofah sponge and 50-60 wt% of water into a plugged Erlenmeyer flask, putting on a plug, carrying out refluxing at the temperature of 60-70 DEG C for 2-3h with stirring, heating up to the temperature of 110-120 DEG C, reacting for 2-3h, cooling, washing by using deionized water, carrying out pumping filtration until a filtrate is neutral, washing by using a few ethanol, and drying in a baking oven of 75 DEG C to obtain the citric acid loofah sponge. The citric acid loofah sponge has strong adsorption capability, can directly used for the adsorption and elution of various metal ions and organic dyes in a water body, is characterized by high adsorption efficiency, fast adsorption speed, good physical and chemical stability and excellent mechanical stability, and can be used within a wide soda acid range. Simultaneously, the citric acid loofah sponge has regeneration capability and is a natural green adsorbent.