A shield-machine cutter wear detection device and a shield-machine cutter system are provided. The device comprises: a plurality of ladder-shaped capacitor network sensors, which are disposed at different positions of a shield machine cutter to generate first electric signals representing the current capacitance values of the ladder-shaped capacitor networks according to the current structures; a signal conditioning circuit, which is connected with the plurality of ladder-shaped capacitor network sensors and is used to condition the first electric signals transmitted from the plurality of ladder-shaped capacitor network sensors to obtain corresponding second electric signals; and a data processing circuit, which is connected with the signal conditioning circuit and is used to determine the wear extent data and the wear shape data corresponding to the positions of the ladder-shaped capacitor network sensors in the shield machine cutter according to the second electric signals. The device realizes accurate detection of the wear extent and the wear shape of different parts of the shield machine cutter.