Gold nanoclusters (AuNCs) have gained popular attention in recent years because of their efficient tumor accumulation through EPR effect and renal clearance. In this work, we put forward a new approach to prepare glutathione-coated, 68Ga-labeled AuNCs (68Ga-GHS@AuNCs) with ultrasmall sizes (< 2 nm) for PET/CT imaging of tumors. GHS@AuNCs has low cytotoxicity in vitro. PET/CT imaging revealed that the 68Ga-GHS@AuNCs could target tumor and be cleared by kidney efficiently. Our study demonstrates that 68Ga-GHS@AuNCs has great potential for detection of tumors.