In order to distinguish different species of wild yellow type Medicago ruthenica， the pollen morphology of wild yellow type M. ruthenica， M. ruthenica and M.falcata were characterized and compared via microscopic observations. It showed that the pollens in wild yellow type M. ruthenic， M. ruthenica and M. falcata were all N₃P₄C₅ type single granules. The pollen size of the two species of M. ruthenica were similar， which were smaller than M. falcate. There are significant differences on the pollen exine pattern among these three forage species. There are waxes covered on the pollen surface of yellow-flowered M. ruthenica and M. ruthenica， while it lacks of wax on the pollen surface of M. falcate. The pollen exine of yellow type M. ruthenica is mainly foveolate with slightly cerebroid-like pattern. The pollen exine of M. ruthenica is generally foveolate patterned， while that of M.falcata is generally cerebroid-like patterned. These results showed that the pollen exine pattern of yellow type M. ruthenica was most similar to M. ruthenica， but significantly different with M. falcata. Thus， the pollen exine pattern could be used as a morphological index for taxonomy of the germplams belonging to different species of M. ruthenica.