The present invention discloses a method for preparing switch transistor comprising: sequentially forming a control electrode, an insulation layer, an active layer, and a source/drain metal layer of the switch transistor on a glass substrate; patterning the source/drain metal layer to expose the active layer; and proceeding an etching process to the exposed active layer in a way of gradually reducing etching rate to form a channel of the switch transistor. The present invention further discloses an equipment for etching the switch transistor. In the way mentioned above, the present invention can minimize the damages to the switch transistor and improve the reliability of the switch transistor.