The invention discloses a power plant non-whole phase protection method. In certain power plant non-whole phase protection methods currently, phenomena of inaccurate non-whole phase protection actions or poor action performance in certain working conditions are likely to happen. In the technical scheme adopted by the invention, according to the available power generator operation condition, non-whole phase protection starting methods under different operation conditions are determined; the sub transient potential and the positive-sequence, negative-sequence and zero-sequence integrated impedance of the power generator in the case of non-whole phase operation in a condition of rated operation of the power generator and full load with auxiliary power are calculated, and on the basis, a symmetrical component method is used for respectively calculating negative-sequence and zero-sequence current at broken lines in the case of a single-phase broken line and a two-phase broken line; setting calculation is carried out on a sequence current starting element in a normal operation condition of the power generator; and setting is carried out on the non-whole phase protection action time. The invention provides the protection method which can act accurately in different working conditions, and the protection reliability is improved.