A small nose sphere-cone is taken as vehicles leading-edge,and kinetic-theory based DSMC method is used to simulate aerothermal environment of hypersonic sphere-cone with different nose radii.Stagnation point heat fluxes calculated by DSMC are compared with that by Fay-Riddell formulae and other theories.Aerothermodynamic characteristics of hypersonic small nose cone with local rarefied gas effect are studied.It is found that the modified Cheng's parameter is a credible criterion in predicting rarefied gas effects at stagnation point of sharp leading-edges.