The Focusing Tomography is presented to reconstruct the 3-D radiation in a luminous body. The 3-D luminous body could be considered as the combination of many 2-D parallel luminous sections. Focus on each section by only one camera, a group of images will be captured which is the overlapped image of one focused image and other defocused images. The irradiances of these images form governing equations. The irradiance distribution of different sections could be induced from above equations. In this experiment, several light emitting diodes are employed to simulate several luminous sections. Results show that this method can reconstruct the irradiance of each section.