To increase the electron temperature of the plasma in the central cell, electron cyclotron resonance heating (c-ECH) is applied. It is observed that both the density and temperature of the plasma decrease during the time of c-ECH, especially in the phase of wall conditioning. To understand the obtained results, plasma parameters including the H measurements at the central and anchor cells are studied. Simulation on magnetohydrodynamical (MHD) stability of GAMMA 10 is also done. It is suggested that sufficient value of the plasma in the anchor cell during c-ECH is necessary for MHD stability of the GAMMA 10 plasma. Related problem to increase the value of the plasma in the anchor cell is pointed out.