Finding an accurate and effective hydrocarbon indicator is important for the future exploration and development of oil and gas resources. It remains a matter of debate as to the generation of low-frequency shadows (LFS) and its application as a direct hydrocarbon indicator in industry. A new hydrocarbon indicator was discovered located inside the hydrocarbon accumulation, which has the typical characteristics of a low-frequency shadow, appearing at a low frequency and disappearing at a high frequency. Therefore, it is referred to as a special low frequency shadow (SLFS). Research findings show that the extent of reservoirs indicated by SLFS is more consistent with known accumulations than the extents indicated by LFS for known the hydrocarbon accumu lation. Furthermore, our results show that SLFS is more accurate in indicating hydrocarbon accumulations than LFS, and even the shape of SLFS is also almost identical to the known hydrocarbon accumulation. Our research could provide an additional seismic detection tool and has the potential to be widely used for exploration and production of hydrocarbon accumulations.