Efficient targeted tumor therapy has long been a major clinical challenge. Traditional targeting methods based on enhanced permeability and retention effect (EPR) have a targeting rate of only ≈5%.To solve this problem, a novel graphene-based tumor cell nucleus targeting fluorescent nanoprobe (GTTN) is a novel tumor targeting mechanism. GTTN is an amphiphilic fluorescent probe with graphene-like single crystal structure, and its periphery is functionalized by sulfonic acid and hydroxyl groups. The probe has the characteristic of targeting specific tumor cells by directly passing through the cell membrane and specifically targeting the tumor nucleus by taking advantage of changes in the permeability of tumor cell membrane in tumor tissues. This new targeting mechanism is called membrane permeability targeting (CMPT) mechanism, which is quite different from the EPR effect. These probes can identify tumor tissue at an early stage and track tumor cell invasion and metastasis at the single-cell level. The tumor targeting rate increased from less than 5% to more than 50%. The achievement of this efficient and accurate targeting of tumor cells will accelerate the arrival of a new era of cancer diagnosis and treatment.