Photolithography is a fundamental and important step in semiconductor manufacturing. It transfers the pattern (the structure of device to be fabricated) from photomask to silicon wafer. However, the traditional mask is un-flexible and costly. Here, an innovative cost-effective thermally-actuated dynamic mask is proposed which has flexibility of switching pattern arbitrarily by dividing the pattern into pixels. In this work, we demonstrated that a micro-shutter array device has the ability to operate as a dynamic mask for optical mask-less lithography. This device utilizes thermal expansion of bi-material cantilever for actuation. It has the ability to switch on and off to enable exposing light to pass through or to be reflected away respectively, thus creating patterns on substrate. The thermal-mechanical characteristics of bi-material cantilever are discussed. The micro-shutter structure is designed, simulated and optimized. The actual device is fabricated by use of normal semiconductor fabrication processes in clean room. The stationary thermal/optical performance and the dynamical performance of device are experimentally measured. The results demonstrate feasibility of applying our designed micro-shutter array device into mask-less lithography as a dynamic pattern generator.