A rice line H7408 and Peiai64S were used to study panicle enclosure characteristics and morphological and anatomical structure of uppermost internode in CMS line of rice．The results showed that there was a significant difference in rate and length of panicle enclosure and rate of stained pollen between H7408 and Peiai64S．Negative correlation was found between panicle enclosure rate，panicle enclosure length and stained pollen rate．Uppermost internode of Peiai64S was 11.88 cm shorter than that of H7408，and the number of external parenchyma cell and internal parenchyma cell were 1016 and 470 less than those of H7408 respectively．Average length of parenchyma cell of uppermost internode was shorter than that of H7408．The length of external parenchyma cell and internal parenchyma cell of Peiai64S in the middle section of uppermost internode was 25.2 µm and 37.8 µm shorter than those of H7408 respectively．Parenchyma cell length of H7408 increased abruptly from basal section to middle section，and decreased slowly from middle section to top section．It is evident that the uppermost internode shortening of Peiai64S is due to the decrease of cell number and the shortening of cell length，and the effect of later is more obvious．