Nanotechnology for early diagnosis and treatment of malignant tumor is a forefront topic in the international field of biotechnology and medicine. In order to improve the effect of cancer therapy, the timely and accurate detection of the cancer is important and necessary. Graphene and its derivatives have various excellent characteristics. For example, biological sensors based on graphene are good at amplifying detection signals, and its derivatives play an important role in the early diagnosis and cancer therapy. In view of this, we discussed the biological sensor application based on graphene and its derivatives in the detection and therapy of cancer.