Using the penetrating voltage and the higher level of exposure could enhance the contrast of the image,thereby the sensitivity of radio graphic inspection was improved.But in order to achieve the high efficiency inspection of the variable cross-section objects,the method with the penetrating voltage and the lower level of exposure called latitude camera was normally used,which decreased the sensitivity of inspection.For demonstrating the changing of the sensitivity between those two methods,theoretical analysis of the interaction between trans-illumination voltage and current had been considered.In addition,a latitude camera sensitivity analysis model of aluminum product was designed.Then the data from the model was analyzed to describe the trend of inspection sensitivity in a latitude camera mode.So in theory,the latitude photography mode has considerable inspection sensitivity;and in practice,the changing law of model sensitivity is verified.When the penetrating voltage increases 40%,the inspection sensitivity still meets the relevant standards.As a result,the latitude camera has reliable inspection sensitivity.