Abstract: The effects of a variable lip on pressure field in an S-shaped air intake at high angle of attack have been investigated experimentally.The measurements of wall and exit static pressures were made at the range of incidence from 0° to 80° of lip angle from 0° to 50°.With increasing angle of the variable lip,two effects exist:(1)the incidence seems to reduced,(2)a door with the same effect as auxiliary air intake door (AAID) occurs behind this lip because of its rotation,which allows air flow with a high kinetic energy into the diffuser.The results show that the pressure promotion is obtained in this kind of intake with the help of the variable lip technique.