The invention discloses a monitoring method and system for leaked machine oil of a relay protection and communication machine room. The machine room comprises various oil charge devices, and types of machine oil used by the oil charge devices are different. The monitoring method comprises the following steps that 1, leaked machine oil in the machine room is sensed; 3, leaked machine oil is collected, and components of leaked machine oil are analyzed; 5, devices, leaking machine oil, in the machine room are judged according to an analysis result, and the analysis result is uploaded. According to the monitoring method, the devices leaking machine oil can be judged out through analysis of the particular components of leaked machine oil, so that workers make a maintenance scheme in time, and safety crises caused by leakage of machine oil are eliminated in time.