A plasma monitoring system includes a plasma chamber performing plasma processes, first and second plasma sensing devices, and a controller. The first and second plasma sensing devices are respectively in a first horizontal direction and a second horizontal direction perpendicular to each other from a center point of a monitoring plasma plane in the plasma chamber. The first and second plasma sensing device generate first and second detection signals with respect to the monitoring plasma plane based on a first incident beam radiated from the monitoring plasma plane in the first horizontal direction and a second incident beam radiated from the monitoring plasma plane in the second horizontal direction. The controller detects two-dimensional plasma distribution information with respect to the monitoring plasma plane by performing a convolution operation based on the first and second detection signals, and controls the plasma processes based on the two-dimensional plasma distribution information.