Digital micro-mirror device (DMD) can be controlled to form Hadamard encoding masks flexibly and efficiently. A kind of Hadamard transform spectral imager of adaptive spectral resolution based on DMD is proposed. The structure and the working principle of the instrument are described and the implementation method of adaptive spectral resolution is analyzed. It can adjust the spectral resolution according to the target and the observational requirements, and a reasonable compromise can be reached between the spectral accuracy and the computation of data. It not only meets the requirements of the target classification and recognition, but also improves the speed of data transmission and processing.