The invention provides a convertible static compensator applicable to a plurality of lines. As for N lines, the convertible static compensator comprises at least one parallel connection transformer, N current converters, a back brake loop and at least N series connection transformers, at least one side of each series connection transformer is in parallel connection with at least one by-pass switch, alternating current sides of the current converters are connected with the at least one parallel connection transformer through the back brake loop to be connected into an alternating current system, meanwhile, an alternating current side of each current converter is connected with at least one series connection transformer through the back brake loop, the series connection transformers are in series connection to be connected into corresponding lines, and direct current sides of the current converters are connected to a direct current bus or mutually connected through change-over switches. By means of the convertible static compensator applicable to the plurality of lines, various operating modes can be achieved, line power flow and system alternating voltage controls can be simultaneously or separately achieved, and excellent flexibility and economical efficiency can be achieved.