High-g combustor (HGC) is a significant branch of the ultracompact combustor, an innovative gas turbine combustor with the ability to shorten the combustor length and improve engine efficiency. To improve the feasibility of the HGC concept, a new HGC was designed to substitute the conventional combustor of a KJ66 small turbine engine. The KJ66 was modified to fit an instrumentation system and test bench to conduct relative experiments. Based on the experiment results, design iterations were conducted relying on simulation methods. The design iteration was comprised of six primary configurations, of which the first four configurations focused on establishing an appropriate high-centrifugal environment to accelerate primary combustion, while the last two modifications focused on improving overall combustion performance. In configuration 4, a pinwheel-shaped swirl inlet was designed to successfully create the high-g environment and balance the flow distribution while bringing insignificant total pressure loss. One modification of configuration 4 was a grid inlet design that divided the inlet channel into several subchannels to constrain the inlet flow and establish an ideal high-g environment. The other modification was a divergent mainstream channel to encourage the dilution process and improve the exit temperature profile. The final design could save at least 1/3 of combustor length while maintaining the same level of performance as the original combustor. Further, the engine was predicted to save at least 12% of the total engine weight and improve at least 14% of the engine thrust-to-weight ratio.