In order to understand the relationship among Hibiscus mutabilis cultivars, the pollen morphology of 19 cultivars were observed under scanning electron microscopy (SEM), and its taxonomy significance was discussed. The results showed that pollen grains of 19 cultivars were usually large and spherical with spine and pantoporate, and granular protrusions on surface. There were differences in pollen grain size and exine pattern among cultivars, which could be used as an important basis for identification of cultivars. The cluster analysis indicated that the 19 cultivars could be divided into 3 types, the pollen grains of type I and II were large with fine tip spines, and those of type III were small with stubby spines and short distance between spines. Therefore, these would provide palynological basis for the studies on the relationship and the classification among H. mutabilis varieties, and also provide a theoretical reference for the breeding of new varieties.