The invention discloses a dehydration, degassing and storage device for insulating oil in the laboratory. The device comprises a vacuum pump, a nitrogen bag, a vacuum glass bottle, a constant-temperature magnetic stirrer and an oil storage tank, wherein the vacuum glass bottle is arranged on the constant-temperature magnetic stirrer and internally matched with a magnetic stirring rotor, an exhaustport of the vacuum glass bottle is connected with the vacuum pump and the nitrogen bag, an exhaust pipeline of the oil storage tank is connected with the vacuum pump and the nitrogen bag, an oil outlet of the vacuum glass bottle is connected with an oil inlet pipeline of the oil storage tank, and an oil taking pipeline is arranged at the bottom of the oil storage tank. The invention also discloses a dehydration, degassing and storage method for the insulating oil in the laboratory. The dehydration, degassing and storage of the insulating oil can be completed by only one set of simple equipment, and the whole process is isolated from air, so that the dehydration, degassing and storage device has the advantages of low equipment consumption, easiness in construction, simplicity in operation,small occupied space and good dehydration and degassing effects, and the influence of excessive moisture or dissolved gas in the insulating oil on simulation experiment results such as breakdown andpartial discharge can be effectively reduced.