The problem of the space charge fields in ECRM has been solved by means of Green function in this paper. The relations between the space charge fields and the guide waves in wave guide have been derived. The parameter called "space charge factor" is introduced in terms of this relations

by means of which the effect of space charge on the dispersion characteristic of ECRM can be taken into consideration.The concept of 5-space is introduced

so that the space charge effect within a guiding centre system as well as between any two guiding centre systems may be taken into account.