Abstract: The performance of optically controlled phased array antenna is greatly improved by the optical phase- shifting network with its advantages of broad bandwidth and high precision, however the additional phase noise of the optical phase-shifting network could lead to the deterioration of the space beam levels. Based on the analysis of the optical phase-shifting networks noise characteristics and phased array antenna theory, the formulas are derived in this paper, with a description of the relationship between the figure of Relative Intensity Noise (RIN) of laser, fiber links insertion loss, laser average power, and the main lobe level as well as the side lobe level. The simulation and theoretical study show that, with the typical parameter in the optical phase-shifting network, the increase of the three parameters is able to lead to reduce the main lobe gain and raise the side lobe level. The impact of RIN on lobe levels is more obvious. To optimize the lobe levels, the relative intensity noise of laser should be less than -140 dB/Hz.