The invention provides a satellite-mounted single flight InSAR system troposphere error correcting method. The method comprises the steps that firstly, a satellite-mounted single flight InSAR system troposphere influence effect model, incidence angle of an auxiliary radar and prior tropospheric zenith delay are used to calculate a two dimensional measurement error introduced by the troposphere ina distance-height plane; then, according to an SAR imaging geometric model, the two dimensional error is decomposed to a three dimensional earth-fixed coordinate system for indication; finally, troposphere error influence of a measured scene is corrected point by point. The method has high correcting precision, can be used to directly handle an interference positioning result, and the operation process is easy.