Tomato (Solanum lycopersicum),one of the most important vegetables, is susceptible to high-temperature injury. High temperature adversely affects its anther development and fertilization, resuting in poor fertilization and fruit set. Therefore, the present study aimed to examine the cellular morphology of anther development and microsporogenesis under optimal and high temperature conditions in a miniature dwarf tomato cultivar, Micro-Tom, a preferred variety for genetic and genomic studies. Based on morphological observation, DAPI staining and anatomical study, the microsporogenesis process of tomato anther could be divided into six stages including premeiotic, tetrad, early uninucleate microspore, vacuolated microspore, binucleate pollen, and mature pollen grain stage. Meanwhile, a defined correlation was found between the flower bud size and the stage of pollen development under optimal conditions, which makes possible the accurate prediction of anther and pollen development stages for the reproductive study. Subsequently, the effect of high temperature stress on the microsporogenesis was checked by the paraffin section assay and pollen viability test, using the flowering plants successively exposed to high temperature ((35±1) ℃/(30±1) ℃,day/night) for 7 days. The results showed that high temperature exposure induced the abnormity of early pollen or the abortion of pollen maturation, leading to the reduction of pollen number and decrease of pollen viability. So the anthers failed to develop maturity pollen under high temperature stress, thereby causing reduced tomato yields. Furthermore, cytological analysis of anther development in tomato plants under different temperature during 6 different periods showed that there was no significant difference in anthers structure between high temperature-treated and control plants at early microspore developmental stages. Their difference was firstly observed at the tetrad stage. The tapetal cells, the innermost cell layer of the anther wall, began to swell under high temperature stress. In the later stage, this abnormal swelling further dilated into the locular space. On the other hand, it led to delay degrading of tapetum as well. Since tapetum supplied nutrients and several enzymes required for pollen development, pollen mother cells stopped to develop into pollen. At the later development stage, the abnormality of connective tissue, endothecium, epidermis, stomium and circular cell cluster was also observed during pollen development. Our data indicated that male sterility under high temperature might be mainly due to malfunctioning of the tapetum resulting in defects in pollen development. The present results will help to understand the basic mechanisms of anther development and microsporogenesis under high temperature condition in tomato.