Abstract: The microsporogenesis and mature pollens in different ploidy Phalaenopsis were observed using squash method，besides，DNA content of mature pollen was analyzed using flow cytometry. The results indicated that there were a few unreduced gametes including haploidy gametes in different ploidy Phalaenopsis. The mean diameter of haploidy，diploidy，triploidy and tetraploidy pollens was 11.4，17.2，19.1 and 20.3 μm，respectively，which was positively correlated with ploidy level（r = 0.935，P < 0.065）. The occurrence frequency of unreduced gamete in triploid（2.39%）was obviously higher than those in diploid（0.59%）and tetraploid（0.67%），suggesting that triploid was prone to producing more unreduced gametes. The unreduced male gametes in different ploidy Phalaenopsis were formed by way of dyad andtriad. The formation of dyads was due to the absence of meiosisⅠin a few microspore mother cells，while that of the triads was probably resulted from the formation of tripolar spindle at meiosisⅡ.

Key words: Phalaenopsis, polyploid, unreduced male gamete, cytological mechanism