Cancer is the second leading cause of death worldwide and poses a significant threat to individuals ,families and society. Rapid and accurate diagnosis of cancer at an early stage is the primary means of mitigating the le- thal effects of cancer. With the development of biosensors ,optical biosensors have received widespread attention. This kind of sensor has the advantages of fast ,real-time ,accurate ,high sensitivity and multiple detection ,and has great application potential in the clinical diagnosis and treatment of cancer. This article discusses the advantages and disad- vantages of existing biosensors for cancer marker detection ,starting with cancer markers. The working principle of pho- tonic crystal fiber and surface plasmon resonance technology are introduced ,and the latest research progress of photon- ic crystal fiber optic fiber sensor based on surface plasmon resonance in early cancer diagnosis is reviewed ,combined with the literature reports of PCF-SPR sensors in the field of biology in recent years. Finally ,the progress of PCF - SPR biosensors in the field of cancer detection is summarized and prospected.