Abstract：In this study, the semiconductor channel layer of poly(ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS)-reduced graphene oxide (rGO) was prepared by solution ultrasonic technology, and the photosensitive materials of tin oxide and zinc oxide quantum dots (QDs) were synthesized by the hydrothermal method. A novel fiber-based organic photoelectrochemical transistor (OPECT) was developed using PEDOT: PSS-rGO gated by SnO₂ QDs-ZnO QDs heterojunction. The electrochemical properties were notably improved due to the synergistic effect of the heterojunction with the channel material. At the same time, serum amyloid A (SAA) biosensors have been developed based on OPECT and antibody modification, showing superior sensitivity of 151 mV/dec in the range of 1 ng/L to 1 mg/L, with good linear relationship (correlation coefficient of 0.9466) and low detection limit. At the same time, it shows good selectivity in other interfering substances and has been successfully applied to detect the SAA content in human serum in real samples. This research combines the new OPECT optoelectronic technology with appropriate flexible fibers for potential applications in portable and wearable bioelectronics devices.