Abstract: The antenna applied for partial discharge detection should maintain high gain in the detection direction, so as to improve the sensitivity to the discharge signals and the signal-to-noise ratio. Due to the large cross-section of power divider, the high-gain steric helical antenna has not been used for partial discharge detection. Single-arm helical antenna and quadrifilar helix antenna were taken as research objects. The antenna structures were simulated by sweep simulation to determine the optimization range, and were further optimized with bandwidth and gain based on the particle swarm optimization algorithm, in order to improve the detection sensitivity and maintain high gain. Appropriative power division network for the quadrifilar helix antenna was invented to minimize volume and improve signal-to-noise ratio. The performance of two antennas were examined through discharge tests, which was compared with commercial helical antennas. The results indicate that the optimized single-arm helical antenna has the advantages of simple structure, small occupied space and multi-frequency narrowband detection. The gain of quadrifilar helical antenna attached by power division network is greater than 5.0 dB in the frequency range of 0.5 GHz to 2.0 GHz, and reaches 6.37 dB at the main resonance point of 1.02 GHz, whose diameter is reduced to 60 mm. The signal-to-noise ratio of quadrifilar helix antenna is superior to that of the commercial planar equiangular helical antenna. Compared with traditional helical antennas, the two antennas keep high gain in lower frequency band and retain axial detection characteristics at each resonance frequency.