Microscopic observation was used to study 2n male gametogenesis and its cytological mechanism inCymbidium sinense‘Xiaoxiang’,C. lancifolium and its thirty-one hybrids to more effectively develop the breeding of polyploids in Chinese Cymbidium. The results showed the occurrence frequency of unreduced male gamete of thirty hybrids ranged from 0% to 9.36%. The average occurrence frequency of consecutive three years was 2.28%,significantly higher that of both male parent (0.22%) and female parent (0.19%). Eight hybrids with average occurrence frequency of more than 3% were obtained. There were significant differences in the average occurrence frequency of 2n male gamete among hybrids. The average occurrence frequency of 2n male gamete in most hybrids was significantly different among different years,indicating that the occurrence frequency of 2n male gamete was not only controlled by genetic factor but also significantly affected by environmental condition. The unreduced male gamete in the interspecific hybrids was produced with both dyad and triad. However,the main way of producing unreduced male gamete was not completely the same in hybrids. The formation of dyads was mainly due to the asynchronous meiotic division of microspore mother cells,resulting in some microspore mother cells not dividing in meiosisⅠand normal division in meiosis Ⅱ,while the formation of triad was caused by the abnormal orientation of the meiotic Ⅱ spindle to form a tripolar spindle in the interspecific hybrids.