The electrical explosion temperature of Ni-Cr thin film bridge was studied by the spectrum radiation method. The radiation intensity was measured at wavelength of 514 nm,631 nm, 692 nm, 715 nm, 910 nm, 1068 nm via six-channel instantaneous optical pyrometer, respectively, when metal thin film bridge fired, and then the ignition temperature was calculated based on blackbody radiation theory. Results shows that when metal thin film bridge is exploded in the conditions of 50 V and 100 μF, the maximum temperature is around 5000 K, and the duration time which the temperature is maintained above 4000 K is 300 ns.