The present application relates to the field of liquid crystal display manufacturing technology, and particularly to a detection device comprising a base, a bracket, a swing lever, a first limit lever and a first magnetic sensor. The bracket is provided on the base, the swing lever is swingably provided on the bracket via a swing shaft and the swing lever is partitioned as a toggle section and a trigger section by the swing shaft, the weight of the trigger section being greater than the weight of the toggle section. An end of the trigger section is provided with a magnetic block, and an end of the toggle section is higher in an initial state than an upper edge of the bracket. The first limit lever is provided on the bracket for limiting the trigger section. The first magnetic sensor is provided on the bracket and located in the vicinity of a virtual extension of the trigger section when the trigger section is limited by the first limit lever. The detection device provided by the present invention can be applied in a liquid environment to accurately detect the position of a workpiece.