The geomagnetic storms occurred in March 2013 and March 2015 resemble each other in many aspects,and both have caused ionospheric disturbances over different regions of China. Based on GNSS observation data from Crustal Movement Observation Network of China(CMONOC),together with observations from ionosondes and a VHF backscatter radar,the ionospheric features over China during these two geomagnetic storms are analyzed and compared. The ionospheric response due to the March 2013 geomagnetic storm was relatively weak. Whereas during the March 2015 geomagnetic storm,intense negative ionospheric storm was observed. The occurrences of ionospheric F-region field-aligned irregularities were enhanced or suppressed during different stages of the storms,possibly due to the effects of different types of storm-time electric fields. The CMONOC data show advantages in ionospheric research because of the large spatial coverage and high temporal resolution.