The heat transfer tubes of steam generator (SG) are the pressure boundary of primary loop of Pressurized water reactor (PWR), and it is an important barrier to isolate radioactive material. The tubes are prone to fatigue, collision and wear caused by random turbulence excitation of two-phase flow. In the analysis of turbulence excitation, it is necessary to determine the random turbulence excitation based on the dimensionless reference equivalent power spectral density (EPSD), the flow parameters of the secondary side and the correlation length. In single-phase flow, the correlation length can be determined based on the tube gap and tube diameter. Two-phase flow contains two components, the correlation length of random turbulence in two-phase flow is more complicated, and few studies have been done. In this paper, an optimized analysis method on the response of SG heat transfer tube under random turbulence excitation is proposed by studying the EPSD and the correlation length in two-phase flow. Compared with the traditional spectrum analysis method, this method can consider many nonlinear factors such as clearance, collision and friction. Furthermore, the characteristics and mechanism of flow induced vibration of heat transfer tubes can be further clarified, and effective measure can be taken at the design stage of SG to effectively reduce the risk of excessive flow induced vibration.