Superconducting Sn films are driven into the non-equililbrium state by tunnel injection of quasi-particles. The voltage across the films starts to appear when injection current increase to a certain value. Near the transition temperature of the Sn films, Tc, the corresponding resistance increase rapidly with increasing temprature. The behavior is similar to the resistance of the normal-superconductor interface. But, the observed effect is orders of magnitude larger than N-S interface resistance and the value of resistance will decrease suddenly, even vanish, when the injection current increases to a higher threshold value I".