COOLANT CONTROL SYSTEM AND CONTROL METHOD OF FUEL CELL

A coolant control system of a fuel cell may include the fuel cell; a coolant line allowing a coolant to circulate therein and connected to the fuel cell to be heat-exchangeable with the fuel cell; an ion removal line provided with an ion filter and connected to a first portion and a second portion of the coolant line to allow a coolant branched from the first portion of the coolant line to pass through the ion filter and then flow into the second portion of the coolant line again; an adjusting valve adjusting a ratio between coolants respectively flowing into the coolant line and the ion removal line; and a controller engaged to the adjusting valve and configured for controlling the adjusting valve based on a temperature of the fuel cell or an output voltage of the fuel cell.