The curved blade design method was used in a vortex axis engine turbine with low aspect ratio to analyze the effect of the curved blade optimization on improving the aerodynamic performance and the flow field structure of the turbine blade with strong secondary flow. Design schemes were determined for 14 curved blades with fixed height and different corners, with the total pressure ratio and flow then obtained through numerical calculation. Preliminary results showed that the negative curved blade prototype is superior to the positive and straight blades, and that the scheme with inflection of 15° is the optimal solution. The changes of the flow ability in the bottom area and the middle area were given based on the density flow along the blade height. Combination of the blade wall limit flow and the static pressure distribution shows that the reverse C type pressure distribution caused by the negative curved blade deteriorates the end zone flow but with low energy fluid in the middle areas greatly reduced, so the overall losses are reduced. The total pressure distribution on the outlet section also shows that the total pressure loss in the end areas increases with increasing passage vortex scale.