Abstract: Observations were made on the flowering and the seed development of Metasequoia glyptostroboides Hu et Cheng. The materials were collected from 23 (-26) year old trees during 1972–1975 in Nanking. The seed abortion belongs to three categories, which are summarized as follows: 1. the degeneration of nucellus at the early stage of its development; 2. the poor development of the female gametophyte; and 3. the incomplete development of the young embryo. A schedule about the strobili (male and female) and seed development in relation to time is given.