Based on the theory of planar array scattering and the idea of antenna shared aperture, this paper proposes a design of shared aperture metasurface (SA-MS) composed by perfect metamaterial absorber (PMA) and artificial magnetic conductor (AMC) in stagger arrangement. The SA-MS not only can achieve wave-absorbing, but also has the function of phase counteraction. The simulation results indicate that the SA-MS can achieve broadband radar cross section (RCS) reduction compared with the surface of perfect electronic conductor (PEC), PMA and PEC-AMC due to cascade connection of frequency band between PMA and AMC . Then the SA-MS and waveguide slot antenna are integrated and fabricated. The simulation and measured results show that the gain of proposed antenna increases by 3.3dB compared with the reference antenna. At the same time, the RCS of SA-MS antenna is reduced by more than 6dB at the range of 5.52-7.51GHz, and the relative bandwidth is 30.5%. The largest RCS reduction reaches 20.5dB and 20.2dB on the condition of x polarization and y polarization respectively. The SA-MS can improve both the radiation and scattering performance of the antenna.