For the stray grain problem of 18 single crystal blades in high efficiency preparation due to the non-uniform temperature field, three different module structures ensure to have same production capacity were designed. The high rate solidification of DD6 Ni-based superalloy under different module structures was simulated by using ProCast software and CAFE model, the influence of the temperature field evolution and the withdrawal rate on stray grains was analyzed. The result showed that the solid-liquid interface of the single-layer module became curved seriously because the cooling efficiency of side close to the center pillar is higher than the side close to the furnace body for the heat preservation effect of center pillar is weak, and it had a large undercooling and tendency to form stray grains. By adding a sleeve to the single-layer module to increase the heat preservation effect, the temperature field can be changed effectively, the degree of bending was reduced to avoid the nucleation of stray grain. The double-layer superimposed module had a uniform thermal and a low undercooling, which could decrease the tendency of stray grain effectively. Both the double-layer superimposed module and the sleeve module could form a complete single crystal when the withdrawal rate was below 100 μm/s, however the diameter of the double-layer superimposed module reduces to a half of the other two, which could reduce the requirement of size of furnace body, it could achieve efficient preparation of single crystal blades.