In order to better solve the problem of passive localization using frequency difference of arrival (FDOA) only, in the case of low time and direction measurements precision, the research status and development direction of passive localization methods based on FDOA are analyzed. On the basis of expounding the basic principles of FDOA passive localization, the nature of localization problems and the classification of localization methods are analyzed. The problems in the localization methods using measurement data and the direct position determination methods using received signals are analyzed respectively, through the summary and comparison of research status at home and abroad, and the future research directions of the FDOA-based localization methods are pointed out. This study can provide reference for the research of passive localization methods based on FDOA.