A rapid-set injection system using high-speed jet fluid for forming a pile-shaped solid body in the ground has an injection rod which does not jam in the ground and which has two or three jet nozzles so that the injection rod linearly excavates the target ground. The injection rod has an excavating bit provided at a lower portion of the injection rod to inject downward a fluid to the outside of the injection rod in criss-crossing diagonal directions, with a drill bit coupled to a lower end of the excavating bit, a first agitating unit mounted to an upper end of the excavating bit to inject desired materials to the outside of the injection rod at different levels in different diagonal directions, and a second agitating unit mounted to an upper end of the first agitating unit to horizontally inject air to the outside of the injection rod.