In order to achieve the 3D distribution of internal components of the sample, we study the confocal 3D imaging reconstruction algorithm based on the synchrotron radiation infrared source. A confocal 3D imaging model is built by the single point detector scanning imaging on the basis of the principle and no-linear characteristics of synchrotron radiation infrared confocal spectroscopy 3D imaging. Based on the characteristics of the forward model, the model of the test sample (an absorption shell) is established to simulate the infrared confocal spectroscopy 3D imaging measurement process, and the raw data of the infrared confocal spectroscopy 3D imaging is obtained. Levenberg-Marquardt algorithm and the modified Gauss-Newton algorithm are used to reconstruct the sample model data. The reconstruction results show that the Levenberg-Marquardt algorithm can reconstruct the 3D information of the sample when no random noise is added to the forward model. When 1% noise is in the forward model, the reconstruction result of Levenberg-Marquardt algorithm has a relatively large deviation with the actual result, but the reconstruction result of modified Gauss-Newton algorithm is accurate.