Chromospheric variabilities of M active stars based on Guoshoujing Telescope

For the M active catalogue of Guoshoujing Telescope (LAMOST), 933 sources are presented in at least two exposures. We found that many M active stars show chromospheric variabilities in the Ca H, H$_{alpha}$, H$_{beta}$, and H$_{gamma}$ lines on short or long timescales.