The invention relates to an implementing method for bipolar commutation failure protection and belongs to the technical field of extra-high voltage DC power transmission protection. The method comprises steps of: acquiring three-phase current of the star side and the angle side of a converter valve in order to obtain corresponding IVY and IVD, acquiring the high-side outlet current IDCP and low-side outlet current IDCN of a valve set, and using a maximum value of the IDCP and the IDCN as ID; performing protection determine logic according to an acquired current signal, determining whether commutation failure happens, and after it is determined that any bridge is subjected to commutation failure, starting any bridge commutation failure counting logic, namely whether corresponding number of commutation failure times happens in an valid time window; outputting an action signal to a control system if a condition is satisfied; if the control system detects that the local pole action signal and the opposite pole action signal satisfy the condition simultaneously, locking the local pole. The method may fast and accurately determine a fault, achieves fast bipolar locking, reduces power fluctuation to an AC power grid system, and improves the safe and reliable operation of the AC power grid system.