The corrosion behavior of 304 nitrogen controlled stainless steel C-ring specimen with constant load in acidic NaCl solution is studied using acoustic emission（AE）and electrochemical noise（EN）techniques.The solution contains 0.5 mol·L-1 NaCl and 1.5 mol·L-1 H2SO4.The ring-down count feature of each AE signal generated during the corrosion process is extracted.By analyzing the ring-down count distribution as a function of time，it is found that the ring-down counts are significantly different in different corrosion stage，which may be used to estimate different stages of corrosion process.The frequency spectrum of AE signal at each main stage is analyzed.The stress corrosion cracking（SCC）of specimen is detected by using AE and EN techniques and the acquired data are compared.The result shows that AE technique is very sensitive to the AE signals generated by 304 nitrogen controlled stainless steel in acidic NaCl solution，so that the corrosion can be detected effectively.The test result of AE is consistent with that of EN，and the combination of AE and EN techniques makes the on-site testing more reliable.