Photoconductive antenna has the advantages of room temperature operation, compact design and wide-band radiation, but its wide application is limited by low radiation power caused primarily by low optical absorptivity. The traditional antenna electrode has no tip structure and the edge electric field is weak, which leads to low light absorption. In order to improve the radiation power of photoconductive antenna, a triangular array antenna electrode structure is designed. The electrode structure is composed of five triangular tips. Finite Difference Time Domain(FDTD) method is adopted to study the electric field enhancement of the electrode and the light absorption of the substrate under 800 nm femtosecond laser irradiation. The results show that this structure increases the area of laser incidence on the substrate and reduces the optical carrier transmission distance. In the case of no electric field, the optical absorption reaches 30.57%, which is 161% higher than that of the traditional antenna. Triangular array electrode structure provides a new idea for the design of traditional electrode structure, which is expected to be combined with nanostructures to further improve the radiation power.