The invention discloses a modified sludge composite adsorbent which is characterized by being prepared from the following raw materials, by weight, 100-150 parts of sludge, 13-17 parts of corn straw, 15-24 parts of peanut shell, 10-15 parts of manganese ore powder, 30-50 parts of zinc chloride, 13-16 parts of magnesium silicate, 5-8 parts of silicon dioxide, 3-5 parts of polyvinyl alcohol, 3-5 parts of polyacrylamide, 2-4 parts of phytoncide essential oil, 6-7 parts of tourmaline powder, 4-6 parts of borax, 6-8 parts of activated alumina and a proper amount of distilled water. By interaction of the added phytoncide essential oil, tourmaline powder, borax, activated alumina, sludge and activated carbon, adsorptivity and bactericidal property of the activated carbon are enhanced. The composite adsorbent is nontoxic and pollution-free, is healthy and harmless to human body, has a good effect when used in water purification, and is beneficial to body health. The adsorbent provided by the invention is nontoxic and environmentally friendly, has advantages of simple preparation technology, wide material source, good chemical stability and high mechanical property, and is worthy of popularization.