The invention relates to a device and a method for controlling a two-cylinder thick matter pump comprising delivery pistons that are actuated in a push-pull manner by means of a hydraulic reversible pump (6) and hydraulic drive cylinders controlled by said pump. For each pressure stroke, the delivery cylinders (50, 50') are connected to a delivery conduit (58) by means of a pipe junction (56). At the end of a pressure stroke, a reversal process of the reversible pump (6) and the pipe junction (56) is triggered. The aim of the invention is to obtain a targeted reversal of the reversal pump and the pipe junction, even when the deliverable quantity is varied, whereby the delivery cylinders are completely emptied, but also without pistons banging the ends of the cylinders. To this end, a computer-assisted reversal device is provided, said device comprising a measuring and evaluating routine for detecting the temporal displacement course of the piston along the path thereof between the two cylinder ends, by measurement and/or calculation, and for calculating a triggering time derived therefrom for the subsequent reversal of the reversible pump and the pipe switch.