The present invention discloses a dry etching method. The dry etching method comprises: etching a first medium layer; introducing a second reaction gas in a reaction chamber, and exciting the second reaction gas into plasmas with a second radiofrequency power, so that the plasmas formed from the second reaction gas are combined with particulate pollutants in the reaction chamber, and in this case the reaction chamber is vacuumized to perform conversion processing; and etching a second medium layer. The technical solution of the present invention is capable of effectively preventing particulate pollutants from falling onto the glass substrate in the procedure of executing conversion processing, meanwhile, the effect of chamber purifying through vacuumizing is improved, and the amount of the particulate pollutants in the reaction chamber is effectively reduced.