In this paper, Fe(1-x)Znx@Zn(1-y)FeyOz nanocrystals were successfully synthesized via a simple programmed microfluidic process (SPMP). The sizes, shapes, crystal structures and surface compositions were characterized by transmission electron microscope (TEM), energy dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that the Fe(1-x)Znx@Zn(1-y)FeyOz nanocrystals (NCs) were mainly composed of iron-rich FeZn alloys and surface coatings are mainly formed by the Fe-doped ZnO. These nanocrystals preserved unique Fe/Zn ratio dependent optical and magnetic properties. A visible green emission at 530 nm and a weak violet emission at 425 nm were observed in the photoluminescence (PL) spectra due to the radiative transition of electrons from antisite defect (Oz(n)) and zinc interstitial defects to the conduction band, respectively, as compared to that in pure ZnO (similar to 379 nm). The PL intensities of these nanocrystals can be increased significantly with the increase of the Zn contents in nanocrystals. The Fe(1-x)Znx@Zn(1-y)FeyOz nano-crystals with a Fe/Zn atom ratio of 2.6/1 preserved the ferromagnetic property, which can be attributed to the high Fe content, varieties of defects caused by ZnFe2O4 shells and the interaction between the shell and FeZn alloy cores. With the decrease of iron content, the coercivities of nanocrystals decreased distinctly. (C) 2017 Elsevier B.V. All rights reserved.