On the basis of the potential field data on 500 hPa from 2000-2010 from NCEP/NCAR, introducing the ideas of EOF(empirical orthogonal function) time-space separation and the dynamic system reconstruction of time series, with the advantages of the global optimization and parallel calculation by genetic assistance, dynamic model inversion is carried out, thus a nonlinear forecast model of the subtropical high activity and aberrance is established. And a mid/long-range forecast of subtropical high activity was carried out. The results of dynamic model forecast experiment showed that the mid/long-range forecast of subtropical high pressure by our model can be very actual. Especially, the aberrance of the subtropical high pressure can be drawn and forecast. A new method of idea is presented for diagnosing and forecasting such complicated weathers as subtropical high activity.