The invention provides an organic waste gas purifying device which solves the problem that an existing organic waste gas processing device easily damages an electrodeless modulator tube. The organic waste gas purifying device comprises a support and a sleeve transversely arranged on the support. An electrodeless modulator tube is inserted in the sleeve. An exciter connected with the electrodeless modulator tube is arranged on the outer side of the right end of the sleeve. The side walls of the two ends of the sleeve are provided with a gas inlet and a gas outlet respectively. The electrodeless modulator tube is sleeved with a cleaning ring. The cleaning ring comprises a supporting cylinder and a rubber cylinder inserted in the supporting cylinder. An annular shoulder is arranged on the inner wall of the right end of the supporting cylinder. A limiting ring is fixed to the left end of the supporting cylinder. The rubber cylinder is clamped between the limiting ring and the annular shoulder. The tube wall of the electrodeless modulator tube is closely attached to the inner side wall of the rubber cylinder. A sealing plate is arranged at the left end of the sleeve. A driving piece capable of driving the sealing plate to slide so as to control the left port of the sleeve to be opened and closed is arranged on the support. The sealing plate is fixedly connected with the limiting ring. The organic waste gas purifying device has the advantage that the service life of the electrodeless modulator tube can be prolonged.