The invention discloses a phase modifier stationing method for preventing multi-DC chain commutation failure, and belongs to the technical field of automation of a power system. A region with a relatively high risk that other DCs are simultaneously or sequentially failure in commutation caused by a commutation failure of a certain DC according to a multi-fed interactive factor is judged, the region is used as an installation region of a phase modifier, and the optimal phase modifier installation place is obtained by calculating and sequencing reactive power improvement control estimation indexes of the phase modifier. By the method, the problems that the commutation failure is judged only by voltage drop of a commutation bus and the inconsistency of a result and an actual condition probably caused by a relevant phase modifier configuration index obtained according to the type of the commutation failure cannot be effectively reflected are solved, and the configuration capacity of the phase modifier is reduced to the great extent on the basis of ensuring rapid recovery of the DC with commutation failure.