NOVELTY - Preparing carbon-base modified sewage purifying agent includes crushing carbon material, adding water, boiling, filtering, drying, and screening to obtain the pre-treat carbon powder; adding chitosan and sodium alginate into deionized water, producing carbon powder modified liquid; taking the pre-treat carbon powder into the carbon powder modified liquid, adding glacial acetic acid, stirring, rolling and shaping; producing chemical modified carbon powder, producing bacteria strain suspension, and producing carbon modified sewage scavenger.    USE - Method for preparing carbon-base modified sewage purifying agent (claimed).    ADVANTAGE - The method has sufficient raw material source, low cost, good absorption performance and degradability without pollution. The raw material is obtained from renewable natural plants.    DETAILED DESCRIPTION - Preparing carbon-base modified sewage purifying agent comprises:    (A) crushing the carbon material, adding water, boiling, filtering, drying, and screening to obtain the pre-treat carbon powder; adding chitosan and sodium alginate into deionized water, producing carbon powder modified liquid; taking the pre-treat carbon powder into the carbon powder modified liquid, adding glacial acetic acid, stirring until the solution is turned into paste, rolling and shaping via a mold to produce the chemical modified carbon powder, where the carbon modified sewage scavenger comprises (pts.wt.) deionized water (100), chitosan (1-45), sodium alginate (3-25), pre-treat carbon powder (40-100) and glacial acetic acid (10-20);    (B) respectively processing activation culture to specific bacteria strains for 24 hours, centrifuging for 10 minutes, washing the sediment via saline solution, centrifuging, repeating for 3 times, diluting via saline solution to obtain bacteria strain suspension, where the physiological saline solution is present at 100 pts.wt.; and    (C) mixing the modified carbon powder with the bacteria strain suspension at a weight ratio of 1:5; mixing and culturing for 12-36 hours; and drying at 20-40 degrees C to obtain the carbon modified sewage scavenger.