Abstract: This paper presents a reflectarray antenna based on slotline-type three-dimensional frequency selective surface. The antenna achieves both high gain and low radar cross section (RCS) simultaneously. The element of this reflectarray is composed of serially connected absorbing and phase-shifting structure, both of which can operate independently. Herein, the absorbing structure is composed of planar slotline and loaded with a lumped resistor in the middle. This structure can achieve a reflection characteristic with absorption at both sides of the reflection band effectively under multimode resonances. On the other hand, the phase-shifting structure consists of a short-circuited slotline. The physical length of the phase-shifting slot is changed to provide phase tuning. It has been verified that the proposed reflectarray antenna exhibits a great radiation performance with gain of 26.82 dBi at 5.5 GHz and an aperture efficiency of 55%. Meanwhile, it achieves RCS reduction of at least 10 dB ranging from 1.2 GHz to 8.8 GHz (the absolute bandwidth of the sing absorbing band is 7.6 GHz while the relative bandwidth is 152%).