The invention discloses a method for preparing phosphorus and a heavy metal adsorbent from alkaline leaching excess sludge and an application method of the phosphorus and the heavy metal adsorbent, and belongs to the field of adsorption materials for sewage treatment. According to the method and the application method disclosed by the invention, the alkaline leaching excess sludge is modified by using a heat treatment method, an internal structure of the sludge is changed, the specific surface area of the sludge is increased, the sludge is enabled to have better adsorptive property, and removal of the phosphorus and heavy metal ion in wastewater can be realized; in addition, the overall adsorbing capacity is higher. The alkaline leaching excess sludge serving as a preparation raw material is industrial waste, and is large in discharge amount; recycling of industrial wastes is realized, and a new idea is provided for dealing with waste by waste. The method disclosed by the invention has the advantages of simple preparation process, lower production cost and convenience in popularization and application.