Abstract: The male sterile line of Chinese cabbage CMS3411-7 and CMS7311, with cytoplasm of Brassica campestris L．were induced under 5 ℃／9 days condition to obtain trace pollens, which relative vigor an d cross-fertile abihty was tested by biological way． Its results show that the quan tity of trace po len in an ther of sterile grade 1,grade 2 and ade 3 were 73．5％-84．4％ ，47．6％-51．5％ (half sterile)and 28．4％-32．5％ of normal anther respectively; the trace pollen in an ther of sterile grade 1 and grade 2 both Can fertile by self-polinated and got about 3.9 grain seeds per silique， which is similar to the situation of low incompatible line； the cross-fertile ability of it is only 9.1％-6．6％ compared with po llen of flowering Chinese cab bage (Brassica campestris L． ssp. chinensis L．var．purpurea Bailey) even pollinated 4 h before．This is about one sixth to one tenth of normal pollen．Additional， we present the qu estion that should be paid attention to in hybrid production， and the reliab ility of using the trace pollen induced to reproduce CMS lines was discussed．

Key words: Chinese cab bage, Tempe rature-sensitive CMS, Vigor of pollen, Cross·fertile ability