High G-loaded rotational flow from aero turbine UCC(Ultra-Compact Combustors) may greatly strengthen heat mass transfer and combustion chemical reaction rates, and high G-load rotational flow is more important influential characteristics in heat mass transfer strengthening process and combustion stabilization. Taking the testing designed UCC model as the study object and using realizable k-ε turbulent model, high G-loaded rotational flow characteristics in UCC such as velocity distribution, high g-load effect, local mutation effect of turbulent energy, axial acceleration effect, velocity radial migration effect, and the fuel particle behaviors are CFD numerical simulated by changing second air injection conditions of circumferential uniform arrangement. The second injection has greatly affected aerodynamics performance among turbine alleyways in UCC, but which has their respective similarity. The effects of second flow on radial velocity among alleyways is few. Fuel spray dispersion has annular and declining Gaussian distribution characteristics. The study results have the same regular pattern with the test, and have reference value to UCC design, analysis and application.