The invention discloses an intelligent vehicle cleaning and oil replacing system and an oil replacing method. A whole oil replacing process including automatic setting and metering, automatic oil quality detection, automatic recovery of discharged oil, oil tank cleaning and new oil injection is achieved through a single-chip microcomputer. The oil replacing operation is stable and efficient in efficiency and quality, and the situations that oil is spilled, and waste is caused due to the fact that oil is contaminated are avoided. In addition, the amount and operation data of the oil replacing process can be recorded by a control system, and functions of memorizing and retracing are achieved.