The present invention discloses a process for treating mirabilite liquid. The process comprises the following steps of: removing mechanical impurities in 35.8 to 36.2 percent original mirabilite liquid which is delivered underground under the monitoring of a DCS automatic monitoring system and the regulation and control of an AK liquid balancing flow meter of which the metering error is between 0.0001 and 0.0002 m<3>/h by using a three to six-stage pipeline filter; and refining and purifying the original mirabilite liquid of which the mechanical purities are removed by using an eight to twelve-stage ion exchanger to prepare mirabilite liquid of which metal ion impurity content is less than 1 ppm so as to obtain refined mirabilite liquid for meeting the production and the application of a variety of mirabilite.