A MEMS (micro-electromechanical systems) reflection-type dualfunction-integrated optical device is proposed. The device employs the compound in-plane and out-of-plane motion of a dual-slope mirror, which is driven by electrostatic actuators, to operate as optical switch and variable optical attenuator, independently. The MEMS-based dualfunctional devices can minimize the overall system size and weight, reduce external interconnections between individual devices, while at the same time maximize system information capacity, optical throughput, flexibility and reliability. Measurements of the MEMS-based dualfunctional devices show that the switching time is less than 9 ms, the excess loss is less than 3 dB and the controllable attenuation range is up to 39 dB, respectively. Moreover, polarization-dependent loss is less than 0.7 dB in the whole attenuation range.