Spinach (Spinacia oleracea L.) is a dioecious, wind-pollinated, and important green leafy vegetable that is widely cultivated worldwide. The characteristics of spinach pollen remain unclear. Herein, we investigated the pollen microscopic morphology of nine spinach genotypes by scanning electron microscopy (SEM). Because pollen grains of spinach are isodiametric and spheroidal, the following data for the pollen properties were observed: the maximum diameter of the pollen (27.66–33.05 um), pore diameter max (1.26–2.57 um), the number of visible pores (30–44), the density of pore elements/100 μm² (4.33–11.00), and the density of spinule elements/10 μm² (4.00–5.33). These are useful characteristics in distinguishing the species. Furthermore, by applying the cluster analysis method, based on key components, nine varieties are categorized into two main classes. These results provide a useful reference for the classification and identification of different spinach varieties.