Thermal management system and method for fuel cell vehicle

A thermal management system for a fuel cell vehicle, comprising:

• a radiator configured to dissipate heat generated from a fuel cell stack through cooling water;
• a de-mineralizer disposed in a branch line branched from a cooling water circulating line connecting between the fuel cell stack and the radiator allowing the cooling water to pass therethrough;
• and
• a 3-way valve configured to selectively introduce the cooling water passing through the radiator or the cooling water passing through a bypass line formed in front of an inlet of the radiator within the cooling water circulating line from the fuel cell stack and includes a first port, a second port, and a third port,
• wherein the first port is connected to a radiator line along which the cooling water passing through the radiator flows, the second port is connected to the bypass line along which the cooling water passing from the fuel cell stack and the de-mineralizer flows, and the third port is configured to be connected to a fuel cell stack side of the cooling water circulating line, and
• the de-mineralizer line along which the cooling water passing through the de-mineralizer flows is branched from a line between a pump and the fuel cell stack and connected to the bypass line in front of the second port such that a flow rate of the de-mineralizer line is cut off when the second port is closed.