The invention discloses a coordination control method for a general dispatcher and an intermediate dispatcher under a back-to-back DC interconnection mode, which comprises the steps that a regional power grid general dispatcher adopts a flat frequency control (FFC) mode, and the provincial power grid intermediate dispatcher adopts a tie-line frequency bias control (TBC) mode; when the system frequency bias is 0.06-0.14Hz, the general dispatcher assists the provincial power grid intermediate dispatcher to implement frequency control, and when the system frequency bias is less than 0.06Hz, the general dispatcher does not participate in the regulation; when the power grid has a DC block fault, the intermediate dispatcher switches the control mode, namely, the TBC mode is switched into the FFCmode, and emergency control is implemented on the frequency; and the intermediate dispatcher recovers the control mode after recovery of the system frequency, namely, the FFC mode is recovered to theTBC mode. The coordination control method improves a system frequency control strategy through an AGC (Automatic Generation Control) coordination control mode, a cooperation mode, an ACE (Area Control Error) calculation mode and an AGC parameter setting mode of the regional power grid general dispatcher and the provincial power grid branch dispatcher, and safe and stable running of the regional power grid is ensured.