The invention discloses a large radio hydraulic oil detecting, filtering and replacing portable device which is characterized by comprising a motor, a gear pump, a particle counter, a flowmeter, a filter, a safety valve, a one-way valve, three quick-change connectors and a pressure difference sensor. The portable device can solve the problem that the current oil cleanliness of an actuator exceedsthe standard under the circumstance that the debugging work of a FAST telescope is not affected, and meanwhile also meets the demand on long-period maintaining work of the FAST actuator. As far as large hydraulic systems with similar demands as concerned, the dimensions and specifications of the components can be also increased to meet the demands.