In this work, the electrocatalytic activity of Ti3C2Tx MXene for phenols oxidation was identified and applied to constructing a cascading catalytic amplification strategy for electrochemical biosensor to determine of BCR/ABL fusion gene, the key biomarker for clinical diagnosis of chronic myeloid leukemia (CML). The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.