In order to improve the sensitivity of biological parameter detection and avoid electromagnetic interference, a photonic crystal fiber sensor based on surface plasmon resonance is proposed for the detection of carcinoembryonic antigen(CEA) solution. The sensor adopts a three-layer arrangement structure of air holes with different diameters. The gold film is plated on the surface of the fiber core as a metal layer, and a specific adaptation layer based on nucleic acid aptamer is added between the gold film and the CEA solution. The full vector finite element method is used to numerical simulate and emulate the sensor. The simulation results show that the sensor has obvious surface plasmon resonance effect in the refractive index range of 1.33~1.41. The sensitivity of the structure can reach 10000 nm/RIU and the linearity is 0.94919.