The invention discloses a multi-component seismic data least squares reverse time migration imaging method and system. The method conducts modification on the basis of the elastic wave reverse time migration method, directly with the multi-component data as input, under the framework of inversion, employs different wave-field propagators and new imaging conditions at different steps of migration so as to achieve multi-component seismic data migration imaging based on inversion. According to the invention, the thought of inversion is introduced to elastic wave reverse time migration, compared with regular elastic wave reverse time migration, a prestack depth migration profile having high precision, high resolution, high signal to noise ratio, and amplitude preservation can be acquired. The method can effectively overcome lineups destructive interference caused by transverse wave polarity-reversal, and can effectively eliminate migration illusion caused by crosstalk among longitudinal and transverse waves while longitudinal and transverse wave vector characteristics, amplitude and phase characteristics are maintained in entirety. The method increases imaging precision, is applicable to multi-component seismic data migration of all kinds of complex medium models, has clear imaging profiles, and is easy for later-stage geology interpretation.