In this paper, a dual-channel spectral imaging system with agile spectral band access and spectral bandwidth tuning capability is presented. A diffractive grating is used as the spectral dispersion element for the dual-channel spectral imaging system. A 4-/ spectral filtering channel using an adjustable slit is set up at the first diffraction order of the grating to realize coarse spectral band selection. An acousto-optic tunable filter selectively filters the spectrum of the non-dispersed zero order to realize fine spectral imaging. The spectral zooming function is achieved without increasing spectral frame number facilitating real-time spectral imaging operation. Feasibility of the spectral imaging has been demonstrated through preliminary experiments. Minimum 6 nm spectral resolution and 1.2° field of view have been achieved. The real-time spectral imaging capable of wide spectral band operation without loosing desired fine spectral capability is particularly useful for a variety of defense, medical, and environmental monitoring applications.