Abstract: To obtain an X-ray source to diagnose micro-mesoscopic state of material with high brightness, good monochromaticity and good contrast in pump-probe technology, and to often ignore the bremsstrahlung line, hence we designed a dual-spectrum diagnostic X-ray source experiments using characteristic and bremsstrahlung spectra. The experiment was carried out on the femtosecond laser beam of the “Xingguang Ⅲ” laser facility of China Academy of Engineering Physics. The laser power density is more than 1.6×10¹⁸ W/cm², with the pulse width of 30 fs by 45° to the target surface. On the other side of the target normal line, the pinhole imaging optical path for characteristic spectral imaging was designed to obtain the focal spot image of 76 μm from the characteristic X-ray generated by the Cu nanoparticle target, larger than the average focus spot of 54 μm obtained by the knife-edge method. On the back side of the Cu target, the bremsstrahlung imaging optical path was designed, and the PIX-ray CCD was used to obtain 2×5 circular Ta group images. Experiments show that the dual-spectral imaging design is reasonable, which is suitable for dynamic diagnosis of micro-mesoscopic materials, and improve diagnosis efficiency.