The compound and the film of the critical charge-ordering Gd0.55Sr0.45MnO3 thin film are prepared using the solid state reaction technique and the pulsed laser deposition method respectively. The properties of the photoinduced relative change in the resistance of the film are investigated. Experimental results indicate that the film exhibits the semiconductive conduction and the charge-ordering temperature is about 70 K from the fitting of a variable-range hopping model. The maximum value of the photoinduced relative change in resistance is about 99.8% when the laser with a power density of 40 mW/mm2 irradiates the film, and the rise time is about 8s independent of temperature. The maximum value of the photoinduced relative change in resistance is about 44% at T=20 K when the laser with a power density of 6 mW/mm2 irradiates the film. The time constant is increased with the increase of temperature, which is attributed to the competition between photoinduced effect and thermal fluctuation.