The invention discloses a three-redundancy server controller achieving power amplification unit fault absorption. The servo controller is applied to a high-reliability new-generation carrier rocket servo system and a guided missile series servo system. On the basis of data communication among three sub-controllers, information interaction and sharing are achieved, and the technic basis is provided for achieving fault absorption of a power amplification unit. Three-redundancy servo valve current signals are collected through a three-way analog-to-digital conversion unit and input to three CPU control units for current monitoring. When one way of power amplification unit has a one-degree fault, the output current of two ways of normal power amplification units is adjusted by adjusting the voltage output of three operational amplifier circuit output ends so as to compensate for the current output of a fault channel. According to the method, one-degree fault absorption of the power amplification units is achieved, the purpose of precisely controlling a three-redundancy servo valve is achieved during one-degree fault of the power amplification units, and when a partial functional circuit has a two-degree fault, the fault absorption function is achieved, and the reliability of the three-redundancy servo controller is improved.