Momentum wheel assemblies (MWAs) play an important role in the attitude adjustment of the satellite by momentum exchange. The micro-vibration induced by the MWAs affects attitude adjustment and leads to unclear imaging and imprecise position. Considering the isolation of multi-directional vibration and transmission of the torque, a novel isolator inspired by rigid-flexible coupling characteristics of folded structure is proposed for the MWAs in this paper. Through the orthogonal arrangement of two Z-folded beams, the isolator has low stiffness in the translational directions and high stiffness in the direction of rotation. An equivalent dynamic model is developed to characterize the isolator. The experimental results verify that the developed model accurately predicts the response of the isolator under different excitations. The results also demonstrate that the prototype can effectively isolate vibration in low-frequency and a wide-frequency range under three excitation directions. Moreover, the isolator has been tested to verify that it has enough stiffness for torque transmission. The design is compact and can be applied to the MWAs of the satellite for multi-direction vibration isolation without influence on the attitude adjustment of the MWAs to the satellite.