The invention discloses a practical layering and zoning reactive power optimization method on the basis of power grid real time data in the technical field of the reactive power optimization of a power grid, which comprises the following steps of: reading in data information which comprises a power grid static parameter, a constraint condition and the power grid real-time data; acquiring effective data for power flow calculation from the read data information; determining an optimization mode and screening the effective data according to the optimization mode; and calculating to obtain a reactive power optimization result by adopting a reactive power optimization method on the basis of an improved immune genetic algorithm. In the method, the number of nodes in an area is effectively controlled by layering according to the voltage class or zoning according to a designated area, so that the calculating time is greatly shortened. Moreover, due to the adoption of the improved immune genetic algorithm, the problem of involving in local optimal solution to converge in advance is avoided.