The invention provides a switch change-over unit redundancy high-voltage frequency converter, which is characterized by consisting of a multiple secondary winding transformer, 3m+1 power units and two switch blocks, wherein the 3m+1 power units comprise one standby power unit, the 3m power units are evenly divided into three groups, and each group respectively forms one phase line of the frequency converter by connecting m power units in series; one output end of the standby power unit is connected with a second phase line; a first phase line and a third phase line are connected with a first switch block and a second switch block respectively, and under the control of the two switch blocks, the first phase line and the third phase line select to be communicated with a first contact or a second contact of the standby power unit; and one end of the first phase line, one end of the second phase line and one end of the third phase line, which are not connected with the standby power unit or the switch blocks form a triphase output end of the frequency converter. The high-voltage frequency converter realizes N+1 unit redundancy function only by the 3m+1 power units, saves two power units compared with 3m+3 power units of the prior art, and reduces the realization cost.