Abstract: The medium-range changes of the subtropical high of June,1979 as influenced by ideal heat sources over the tropical western Pacific are studied using a global circulation spectral model.The analyses of the simulation results show that the subtropical high and mid high latitude circulation systems of the eastern China are changed by the ideal heat source 4 days after inclusion.In the easterlies south of the subtropical high,the disturbance is produced,propagated to the northwest at first.Then,this disturbance branch off into two parts in the westerlies,one still propagating to northwest,another changing into the eastnortheast direction in the westerlies stream of the north of the subtropical high.Owing to the influences of the two disturbances,the subtropical high and westerly system are changed.