Abstract: In this paper,the karyotype of Pinus Koraiensis Sieb.et Zucc. Was studied and analysed in detail.The results indicated that its chromosome number is 2n=24.All of the chromosomes of 1st.to 11th.pairs are metacentric chromosomes and the lenth of neighboring chromosomes seems to be very similar.The 12th.chromosome pair being very much shorter than 1st.to 11th.pairs shows submedian centromeres and distinguishes easily from other chromosome pairs under microscope.There is an apparent secondary constriction on the short arms of chromosomes of 5th.pair.It was observed that some times the clear band patterns are showed on several chromosomes without cold pretreatment and staining,especially on the short arms of 8th.and 10th.pairs of chromosomes.