By using the daily NCEP/NCAR reanalysis dataset and the observation data, based on the improved comprehensive meteorological drought index (CI), the Low-Frequency Oscillation (LFO) characteristics in the drought processes in spring of 2011 and in summer of 2013 over mid-lower reaches of the Yangtze river were analyzed. Results show that the major LFO period of the spring drought process in 2011 is 30-60 d. Westward movement of positive anomaly of 500 hPa low-frequency height field over western Pacific, eastward and northward movement of positive anomaly of 500 hPa low-frequency height field over upper reaches of southern branch frontal zone and southward movement of lower level low-frequency anticyclone over eastern Northwest China may be the important reasons of the variation of low-frequency CI. The major LFO period of the summer drought in 2013 is also 30-60 d. Southward movement to South China of positive anomaly of 500 hPa low-frequency height field over West Asia and western Pacific and westward, northward movement of lower level low-frequency anticyclone over the Bay of Bengal and western Pacific have an important connection with low-frequency CI variation.