Abstract: Wind turbines have been serving in harsh environments for a long time, and the corrosion of acid rain is an important factor affecting the safe operation of the tower during service. Taking the welded joint of Q355E steel as the research object, the corrosion rate and acoustic emission signal of Q355E steel welded joint in different corrosion stages under the simulated acid rain environment are discussed through the electrochemical and acoustic emission methods, and the effective discrimination of corrosion degree is formed by the scanning electron microscopy and energy spectrum analysis. The results show that the corrosion rate of the joint increases first, then decreases, and then increases and gradually tends to be stable, and there is a weak diffusion in the early and late stages of corrosion. The acoustic emission signals are mainly metal dissolution signals and corrosion product accumulation, passivation film rupture and bubble rupture signals; and it has a wider range of frequency domain in the metal dissolution stage and the corrosion product accumulation stage, mainly concentrating at 90~190 kHz and 110~190 kHz.