Abstract: In this article, the karyotype of "Mongolian pine" in the north-eastern China was reported in detail. Results indicated that the karyotype of "mongolian pine", found on the mountains was similar to that of European pine (Pinus sylvestris) while that of "mongolica pine", found on the sandy soil was obviously different from them. Based on this comparative study of the karyotype, the authors concluded that, it is reasonable to admit the amongolian pine", growing on the mountains as the typical Pinus silvestris, and the "mongolian pine", growing on the sandy soil as P. sylvestris var. mongolica Litv.