This paper reports the design of a novel twisting-type micromirror actuation system. The actuating mechanism for driving the micromirror combines two paralleled bimorph actuators bending in opposite directions for rotational control of the micromirror. Each actuator is structured by gold and silicon dioxide or nickel and silicon nitride thin films with embedded polysilicon line heaters. With a size of only $15{mu}m$ in width, $1.3{mu}m$ in thickness, and $100{mu}m$ in length, two bimorph actuators can result in a vertical displacement of $25{mu}m$ at 10 volts dc with the span of $120{mu}m$, and thus the micromirror can rotate by angles over $20^{circ}$, which is a significant improvement, compared to conventional tilting-type micromirrors.