Disclosed is a retro-reflective type optical signal processing device and method, particularly to a device includes a set of optical mirror planes with retro-reflective type layout and configuration, and a set of micro-shutters controlled by microelectromechanical actuators, whereas the optical signals in propagation can be blocked or partially blocked in terms of the position of said a set of micro-shutters corresponding to the optical signal transmission path, thereby the method of said approach to determine the range of attenuated optical signal is a variable optical attenuation function demonstrated by present invention. Such a retro-reflective type optical signal processing device and method further comprises a set of three reflective mirrors and micro-shutters with reflective mirrors. Thereby this device has the capability to switch 2 sets of retro-reflected optical light transmission paths, the method of said approach is a demonstration of 2null2 optical switching function.