The invention discloses a method for judging the position of a failure cell in an energy storage type sodium-sulfur cell module. The energy storage type sodium-sulfur cell module consists of a plurality of sub-loops which are sequentially connected in series; each sub-loop is formed by connecting a plurality of sodium-sulfur cell series-connection units with one another in parallel; each sodium-sulfur cell series-connection unit is formed by sequentially connecting a plurality of single sodium-sulfur cells in series; and the position of the sodium-sulfur cell series-connection unit in which the failure cell is located is judged by comparing the comparison voltage of each sodium-sulfur cell series-connection unit and the variation rate of the end voltage of each sodium-sulfur cell series-connection unit. According to the method provided by the invention, the quantity of voltage collection wires led out from a thermal insulating box is greatly reduced on the premise of ensuring that the position of the failure cell is accurately judged, so that the wiring manner is relatively sensitive, a heat radiation channel of the thermal insulating box is reduced, and the thermal insulating box keeps a constant temperature. Meanwhile, the volume of data collected by a cell management unit is further greatly reduced, and system resources can be saved.