The invention provides a photoetching machine wafer stage dual-stage switching system which comprises a wafer stage running on an exposure working position and a wafer stage running on a pretreatment working position; the two wafer stages are arranged on a base station and suspended on the upper surface of the base station by an air bearing; each wafer stage is passed through by a lead rail alonga Y direction; one end of the lead rail is connected with a master drive unit; the two wafer stages can move in the Y direction along the lead rail; the other end of the lead rail can be in abutting joint with an X direction unidirection auxiliary drive unit; and the movement of the wafer stages in the X direction is realized under the drive of the unidirection auxiliary drive unit; the unidirection auxiliary drive unit and the Y direction lead rail can separate and be in abutting joint precisely so as to realize the position switching of the two wafer stages. The system avoids the defects that when the wafer stages switch, the air bearing steps across a guide face to switch to give rise to the accuracy requirement of dimensional uniformity of the skyscraping wafer stages and high accuracyof processing and assembling of spare parts, thus greatly simplifying the system structure; in addition, the system is driven by adopting a center of mass so that the accuracy of the system is greatly increased.