In this study, the spring wheat cultivar ‘Yangmai 15’ and the semiwinter cultivar ‘Yannong 19’ were used as experimental materials, which were performed low temperature treatment at 6-8 days after anthesis. Then the wheat caryopses at different developmental stages were sampled after anthesis. The microstructure characteristics of the pericarp, endosperm and nutrient transport tissue were observed using resin section technology, and the microstructure characteristics of wheat caryopsis development under low temperature conditions after flowering were explored. The results showed that: (1) the low temperature after anthesis delayed the early and middle development of caryopsis of the two wheat cultivars, delayed the filling stage of Yangmai 15, shortened the filling stage of Yannong 19, and finally reduced the grain weight of the two wheat cultivars. (2) Low temperature treatment after anthesis slowed down the apoptotic rate of pericarp cells of early wheat endosperm development and the degradation rate of amyloplast in pericarp cells. (3) The low temperature after anthesis significantly reduced the accumulation of amyloplast and protein bodies in the early and middle stages of wheat endosperm development, shortened the filling period, and reduced the degree of endosperm fullness. (4) The phloem of wheat caryopsis developed slowly under low temperature conditions after anthesis, and the distribution range of sieve tubes was reduced. At the same time, the development of endosperm transfer cells slowed down, and the number of wall ingrowths on the cell wall was significantly reduced. The study found that low temperature after anthesis delayed the early development of caryopsis of the two wheat cultivars, which was reflected in the delayed apoptosis of pericarp, the decrease of storage material accumulation, the underdevelopment of nutrient transport tissue, the decrease of endosperm fullness and the decrease of dry weight of single caryopsis. At the same time, there were differences in the response of the two wheat cultivars to low temperature. At low temperature after anthesis, the caryopsis filling period of spring wheat was prolonged and that of semiwinter wheat was shortened.