The utility model discloses a spraying device of a magnetic particle flaw detector. The spraying device comprises a spraying head and a spraying pipeline, the spraying pipeline is composed of a plurality of columnar short pipelines; a threaded connector is arranged at one end of the short pipeline; a connecting sleeve in threaded connection with the threaded connector is arranged at the other endof the short pipeline; a sealing washer is sleeved on the connecting sleeve; each short pipeline is in threaded connection with an electromagnetic mechanism for adsorbing magnetic powder; the electromagnetic mechanism comprises a sealing rubber column, an electromagnetic iron core is fixedly arranged in the sealing rubber column, a fixing sleeve in threaded connection with the interior of the short pipeline is fixedly arranged on the upper half portion of the sealing rubber column, a limiting disc is fixedly arranged at the end, close to the fixing sleeve, of the sealing rubber column, and a power interface is formed in the limiting disc. The pipeline can be cleaned, and the phenomenon of magnetic powder blockage is avoided.