Taking planar phased array antenna as the research object, the calculation method of the beam-control code is described in detail on the basis of the function model of the front antenna pattern. The architecture of the beam-steering system is analyzed. The calculation method of beam controlling code is put forward by combining lookup table method with distributed computing. The software processing flow is expounded, and the technical advantages of this method are compared with the traditional methods. The simulation analysis of the antenna pattern shows that the method can control beam pointing and realize one-dimensional scanning and two-dimensional scanning, one-way scanning and omnidirectional scanning with good accuracy. This work has important guiding significance for the design of the beam controlling system, and can be extended to other array antenna models.