The present invention relates to a method for adjusting a single stand reversible rolling mill, in particular to a method for adjusting housings outside the single stand reversible rolling mill, which comprises the following steps: a, determining that a housing base reaches assembly accuracy, and suspending the housings to correct positions; b, hanging a steel wire, checking vertical and transverse central lines of the rolling mill; c, connecting earphones to the vertical and transverse central lines of the rolling mill by lead wires; d, moving housings on a transmission side and an operation side towards the housing base direction on a discharge side respectively by a hydraulic jack to ensure that a bracket side of the housings is close to the lateral surface of the base on an outlet side, and moving a rail rest on an inlet side towards the outlet side; e, adjusting sizes of the housing rolling center and the transverse center of the rolling mill, and fastening a foundation bolt by 70 percent of a design torque; and f, hanging steel wires on housing windows and the rolling directions of the housings, and measuring the verticality and the horizontality of the windows and the rolling directions of the housings of the rolling mill. The method uses the steel wires and the earphones to ensure numerical reading, eliminates reading errors caused by visual errors of staff, and improves the assembly accuracy of equipment.