The flow-field and combustion processes of hybrid rocket with different chamber structures under 2-D and axisymmetric environment was numerically calculated.Analytical result indicates that the fuel regression rate increases with the increase of pre-chamber length

but the acceleration is smaller and smaller

and the tendency to characteristic velocity and vacuum specific impulse with increasing pre-chamber is bigger at first and then smaller and keeps steady in the end.The fuel regression rate does not change when the post-chamber extends

and the characteristic velocity and vacuum specific impulse become higher with longer post-chamber.The draw ratio of grain does not affect the fuel regression rate distribution along the axis under the condition of the same oxidizer mass flux.Both draw ratio and average fuel regression rate have the same changing trend

but speed of the increase of average fuel regression rate is smaller and smaller.The characteristic velocity increases with draw ratio firstly and then decreases

and the position of the maximum is around draw ratio of 10.0.Fuel regression rate increases with draw ratio with the same theoretical oxygen/fuel ratio

but this does not affect its distribution tendency;combustion efficiency reduces firstly and then increases gradually with of the increase of draw ratio;actual oxygen/fuel ratio decreases gradually when draw ratio becomes large and the change tendency is slower and slower.