A new type of spectrometer design for confocal-spectral microscopy is proposed in this paper. Spectral imaging is the technique to collect spectrum information of the sample at each point. By combining with the confocal microscope, the sign al related with the position including z-axis and the wavelength can be measured. To select appropriate wavelength ban d detected by PMT channel, various methods can be used as occasion demands. In this paper, it is proposed that the dispersed sign al is scanned by a galvano mirror to change the wavelength. Also, Acousto-optic tunable filter (AOTF) is used to diffract specific excitation light and to divide excitation and emission signals. Because of the birefringent characteristics in AOTF material, the emission lights experience different paths according to their polarization states. This effect is analyzed and compensated by using an additional birefringent material.