A high length-to-diameter ratio of a rocket leads to unstable flight performance, affects structural loads, and makes a high dry mass of the rocket with a diameter constraint. To improve the volumetric efficiency of the fuel, a multiport design with optimum O/F ratio was considered by adjusting the number of ports and diameter while decreasing the length. To optimize the O/F ratio, the final port diameter was predicted, and the arrangement of the ports to prevent the merging of the ports was considered. The length of the fuel content was reduced to 30% when the number of ports was 14, compared with the single-port fuel. The experimental result showed a slight decrease in the O/F ratio with the increased number of ports and reduced length of fuel at the same oxidizer mass flow rate, and the characteristic velocity efficiency increased. Peak-to-peak pressure amplitude in the prechamber was calculated to compare the effect on the amplitude of the multiport fuels. The application of the simple cylindrical multiport design reduces the length-to-diameter ratio of the hybrid thruster and improves rocket combustion performance.