Abstract:In the karyotype of Paris cronquistii,the variations of chromosome structure and a series process of B-chromosomes produced by break kage of secondary constriction of satelite chromosome were found.These interesting phenomena were received by observation of experiment. The occurrence,accumulator and transmittal of B-chromosome are discussed in this paper. The author recognizes that the breakage of secondary constriction of satelite chromosome has relation to origin of B-chromosome.