The high-carbon austenitic stainless steel Super304H developed on the basis of traditional 304 stainless steel has excellent high-temperature performance and is widely used as superheater and reheater tubes in the ultra supercritical units. However, its high intergranular corrosion sensitivity (IGCS) caused by the high carbon content has become a key issue affecting the safe operation of the ultra supercritical units. Researchers have made a comprehensive studies, like composition optimization, improvement of heat treatment and adjustment of self-healing technics, trying to seek an effective method to reduce the IGCS of Super304H steel. After a brief introduction of the mechanism of intergranular corrosion of austenitic stainless steel, this paper focused on the research progress of various countermeasures for intergranular corrosion protection of Super304H steel in recent years. Conventional methods such as selecting the lower limit of C content, adding Nb stabilizing element and double solution treatment were found to be not able to curb completely the IGCS caused by the formation of M23C6 of Super304H steel, so another way has to be explored. Surface nanocrystallization by shot peening (SP) was found to accelerate the formation of M23C6 and the healing of chromium depleted zones of Super304H steel, and as a result, rapid desensitization could be obtained. However, severely deformed microstructure by SP triggered the abnormal precipitation of chromium-rich sigma phase during aging, resulting in the deterioration of intergranular corrosion resistance of the steel. Therefore, a critically unsaturated SP process that could avoid the abnormal sigma-phase precipitation was investigated by optimizing the SP technics. The obtained SP process is the optimal one for rapid self-healing and desensitization in the chromium-depleted zones of Super304H steel. Meanwhile, the surface nanocrystalline can keep a good thermal stability and the desensitization treatment does not have a negative impact on the uniform corrosion performance of the Super304H steel. Finally, the development direction of intergranular corrosion protection technology of austenitic heat-resistant stainless steel in the field of ultra-supercritical units is prospected.