Numerical simulation of the basic flowfield with controllable Mach number distribution is conducted at Ma∞=4.0—7.0 to study the influence of design Mach number Mai, which shows that reducing Mai can obtain higher mass coefficients, pressure ratios at high Mach number and shorter length. The hypersonic inward turning inlets with circular shape intake are designed based on the basic flowfield of Mai=5.5,6.0 and 6.5. The numerical simulation results of Ma∞=4.5—7.0 indicate that the inlet based on the basic flowfield of Mai=5.5 has better mass capture ratio and pressure ratio, which is almost consistent with variation of basic flowfield. The influence of design Mach number Mai on total pressure recovery coefficients at exit plane becomes smaller.