Abstract: The purpose of this study was to select the suitable broad-spectrum stain for the determination of walnut pollen viability, determine the pollen viability of walnut, screen the suitable storage temperature for maintaining walnut pollen viability, and study the pollen morphology, which can provide a basis for walnut cross breeding and variety identification. In this study, six walnut cultivars mainly grown in Shaanxi were used as materials, the staining effect of TTC, MTT and I₂-IK stains on walnut pollen was studied by single factor experimental design with medium method as control, the changes of walnut pollen viability were compared at room temperature of 20 ℃, 4 ℃ and-20 ℃, and the pollen morphological differences of 6 walnut cultivars were studied by scanning electron microscopy. The results showed that active and inactive pollen could be identified by MTT but TTC and I₂-IK could not. The pollen variability determined by MTT and medium method was consistent among 6 walnut cultivars. The initial pollen viability of 6 walnut cultivars was divergent greatly, and the pollen viability of ‘Zhonglin 5’ and ‘Xiangling’ was significantly higher than that of other 4 cultivars. The pollen viability of walnut could only be maintained for 4-5 days at room temperature of 20 ℃ with 20% water content. The pollen life can be effectively prolonged for 5-9 days at 4°C, and the pollen viability of most cultivars can only be maintained for 2 days at-20 ℃. The pollen grains of 6 walnuts were nearly spherical, and the size of pollen grains was significantly differences among cultivars, in which the polar axis ranged from 39.15 μm to 44.35 μm, and the equatorial axis ranged from 33.58 μm to 42.86 μm. The pollen grains of ‘Qingxiang’ and ‘Shaanhe’ were relatively large. The pollen grains of walnuts had 13 to 20 round or oval germ pores with the long axis ranging from 3.26 μm to 3.75 μm, and the short axis ranging from 2.75 μm to 3.35 μm. The germ pores number differed significantly among cultivars. This study estimated that the stain MTT had low selectivity and broad spectrum in pollen staining of walnut cultivars, which can be used as the preferred dye for walnut pollen viability determination. The pollen life of 6 cultivars was short in natural circumstance, the initial pollen viability was relatively low（less than 40%） besides there was great diversity among cultivars. The storage at 4 ℃was favorable for walnut pollen storage whereas-20 ℃was unfavorable. There were significant differences in pollen grain size and germ pore number among 6 walnut cultivars.