The fishbone instability induced by the trapped energetic electrons is studied with off-axis and on-axis ECRH in HL-2A tokamak. Numerical results show that the fishbone can be triggered by energetic electrons if the poloidal beta βh is higher than a critical value βh,crit . In addition, its real frequency increases with the increasing of poloidal beta βh and equals the toroidal precession frequency of energetic electrons.Furthermore, the critical value βh,crit decreases with higher density peaking of energetic electrons and approaches a constant by more peaked density profiles. And besides, analysis of the effects of the pitch angle and the turbulent energy on real frequency and growth rate is carried out. It can be seen that the growth rate curve has a local minimum value if the pitch angle α0 =1 , which indicates that the fishbone instability can be stabilized by the barely passing energetic particles. Moreover, it can also be seen that the real frequency increases with the increasing of the turbulent energy δWˆc , while growth rate decreases. It indicates that the background plasma tends to stabilize the fishbone instability.
