The invention provides an on-line monitoring device and a method of mining overburden stratum movement of a shallow coal seam and belongs to the field of monitoring equipment for coal mines and metal mines. The shallow coal seam is buried shallowly, after the coal seam is mined, a stratum controlling the overburden stratum movement is just a key layer, and not all strata are required to be monitored, so that the device and the monitoring method can monitor multiple strata simultaneously movably. The device comprises a ladderlike compressor, pressure sensors, a converter and a data acquisition device. The ladderlike compressor is connected with the pressure sensors; an inner rod of the compressor moves down due to sinking movement of an overburden stratum; the pressure sensors generate signals and are connected with the converter; the converter converts pressure signals into data signals; and the data acquisition device is connected with the converter and acquires data converted by the converter. The device and the method realize real-time monitoring of the overburden stratum movement of the shallow coal seam through data acquisition, data transmission and data processing, and can visually show overburden stratum movement and deformation.