The invention relates to a method for improving the time-lapse seismic difference recognition capability of a thin reservoir. The method comprises the steps of performing amplitude preserving and consistent processing on original seismic data and monitored seismic data; directly performing differencing processing on the original seismic data on which amplitude preserving and consistent processing are performed and the monitored seismic data on which amplitude preserving and consistent processing are performed so as to acquire differential seismic data; performing phase conversion processing on the differential seismic data by adopting a phase conversion processing method of seismic signals so as to acquire differential seismic data after phase conversion. Through phase conversion processing, the method effectively solves problems of high explanation multiplicity and low achievement reliability of remaining oil distribution which are caused by a condition that the time-lapse seismic difference of a thin reservoir is not easy to be recognized because of disperse waveform and weak energy. The method can be widely applied to recognition for time-lapse seismic difference in the time-lapse seismic implementation process, the time-lapse seismic difference recognition performance is improved, the reliability of an oil reservoir remaining oil distribution prediction achievement is increased, the recovery ratio of an oil field is improved, and the development life of the oil field is prolonged.