Abstract: Compared with the traditional methods of the correlative interferometer，the phase differences interpolation algorithm has higher accuracy but complex calculation.A secondary correlation method of direction finding by using phase differences interpolation algorithm is proposed.Firstly，the region of incident wave direction is roughly found.Then the standard library is enriched by the phase differences interpolation operation.Finally the maximal correlative direction through the second correlative calculation is found out.Simulation results show that the improved method has a much higher calculating speed while assuring good precision.