The invention discloses an electricity selling business comprehensive service system with an electric quantity prediction function. The electricity selling business comprehensive service system comprises an electric quantity prediction module, a contract management module, a supply and demand matching module, a user electricity charge module, a settlement management module, a market data summarization module, a deviation management module and an online monitoring module. According to the invention, an electricity selling company can be assisted to accurately grasp the operation direction, market dynamics, supply and demand dynamics and the like; the electricity selling business management efficiency is improved, thus reducing transaction risk, and securing maximum responsive efficiency; meanwhile, working means such as work cooperation, information communication, operation decision and auxiliary analysis are provided for electricity selling companies and power consumers; the basic requirements of user information collection, arrangement, analysis, reporting, confirmation and information management, electricity bill analysis and calculation, bilateral transaction electric quantitydecomposition, electric quantity adjustment, quotation simulation, quotation analysis, electric quantity prediction, operation analysis, deviation assessment simulation, service management, user archive management and the like in the electricity selling service management are met.