A new strategy aiming to achieve post-fabrication performance tuning capability for terahertz metamaterial absorber (MMA) was proposed. Different from conventional mechanical tuning methods (e.g. external stretching or bending), a more convenient tuning mechanism with build-in pneumatic actuator was adopted, in which the suspending membrane based pneumatic actuation mechanism integrated with microchannel network was designed, through which geometry of the metal structure sitting on the membrane (constructing the unit cell of MMA) can be changed. With respect to the applied positive or negative pressure, opposite membrane deflection as well as the induced geometry change in the metal structure can be obtained, thus achieving dual-side absorption peak tuning.