Abstract: Seven-species air model was used and electrical conductivity was calculated by species formula to investigate the effects of the intensity of uniform magnetic field on three dimensional chemical nonequilibrium hypersonic flows around a blunt body by solving the viscous MHD(magneto-hydro-dynamics) equations.The results show that the shock standoff distance is increased and total drag coefficient and wall temperature are reduced with increasing external magnetic field.At B_y=0.03 T,the shock standoff distance is increased by about 7%,total drag coefficient and local wall temperature in nonequilibrium flow are decreased by about 5% and 74%,respectively.However,in frozen flow under the same conditions,the shock standoff distance is increased by about 43%,total drag coefficient and local wall temperature are decreased by about 6.9% and 18%,respectively,as compared with that without magnetic field.