The present invention provides a moving-point target detection method based on passive microwave interference imaging. The method for processing image data includes: performing image inversion under sparse sampling image data according to a passive microwave interference principle; performing data averaging to the multi-frame images obtained from image inversion to be regarded as background estimation; weakening the background in each frame image and obtaining the processed images; based on the sampling characteristics, using a cleaning method to clean the processed frame images and obtaining the cleaned fame images; performing target positioning in each cleaned frame map; and then identifying the target trajectory of the moving-point target. The moving-point target detection method of the present invention makes full use of the multi-frame image information to weaken the influence of the background on the moving target detection. Based on the processed images after the separation of the background, the Clean method is used for cleaning treatment, which can precisely identify and extract the moving trajectory of a moving-point target.