The invention provides a monitoring and diagnosing system for oil harvesting equipment. The monitoring and diagnosing system comprises a remote monitoring subsystem and an on-site diagnosing subsystem, wherein the remote monitoring subsystem comprises a diagnosis command sending module, a remote receiving module and a display control module; and the on-site diagnosing subsystem comprises an evaluation network generation module, a data receiving module, a fault diagnosing module, a real-time database and a historical fault database. According to the monitoring and diagnosing system, a fault assessment network is established by using historical fault data, so that the accuracy of fault assessment can be ensured; the set fault data is added and enters the historical fault database, so that the historical fault database can be continuously expanded, and the reliability and accuracy of fault evaluation are enhanced.