The 3.0 Ga Tiejiashan granite in the Anshan area is the oldest and largest potassium granite intrusion in the North China Craton. Meta-sedimentary rocks with high maturity in the Tiejiashan granite were once considered to occur as enclaves and to be a main resource from which the Tiejiashan granite came. However, SHRIMP U-Pb dating of detrital zircons from three meta-sedimentary samples commonly gives the ages of -3.0 Ga, being the same as the formation time of the Tiejiashan granite. Therefore, the supracrustal rocks should have been formed after 3.0 Ga, with a tectonic relationship with the granite. It is considered that the supracrustal rocks dated in this study are a part of the 2.5 Ga Anshan Group.