The invention discloses an off-network photovoltaic power station internal harmonic wave load index prediction method. The method is mainly used for controlling operation strategies of a photovoltaic power station. The method comprises steps of carrying out real-time monitoring on operation parameters of the photovoltaic power station and meteorological environmental parameters; establishing an off-network photovoltaic power station internal harmonic wave load index evolution time sequence; constructing m-directional phase space for measuring data time sequence; carrying out heredity-ant colony mixing algorithm processing after the construction of the phase space; and calculating the off-network photovoltaic power station internal harmonic wave load index. Through the mutual cooperation of the four steps, the operation strategies of the photovoltaic power station are controlled according to the calculation result in real time, so the electric energy quality of the photovoltaic system can be effectively improved and reliability and economy of a regional electric power system are remarkably improved.