The invention discloses an eight-input balance function block structure and method for a thermal power generating unit. The eight-input balance function block structure comprises an engineer station,an operator station, a switch, a controller, a first analog quantity input terminal board, a first analog quantity input card component, a second analog quantity input terminal board, a second analogquantity input card component, a switching value input terminal board, a switching value input card component, an analog quantity output card component, an analog quantity output terminal board, a switching value output card component and a switching value output terminal board. The structure is clear and simple and can support eight paths of parallel equipment to carry out balance operation, wherein a transmission mode and a non-transmission mode are flexibly switched, a normal working mode and a balance working mode are supported in the non-transmission mode, and three value taking modes ofa maximum value, a minimum value and a mean value are supported.