Oily sewage with high salinity, calcium, magnesium, barium, strontium carbonate and sulfate radical ion will scale with the temperature and pressure changes, so the production decline, and even affect the normal production. PAMAM G0 and other scale inhibition dispersion agent can be prepared to composite multiple scale inhibitor and dispersant, less amount of it can prevent the calcium carbonate, calcium sulfate, barium sulfate, silicate from depositing in oilfield water flooding system and has wide application range, not only suitable for high temperature, high salinity, high alkaline conditions, but can also be used in oilfield water injection system in high temperature, high salinity and acidic conditions. Weihai CY Dendrimer Technology Co. Ltd forwards from "A Kind of Composite Multiple Scale Inhibition Dispersing Agent for Oilfield Water Injection System and its Preparation", Shanghai Meijing Environmental Protection Materials Co., Ltd.