Endophytic fungi were isolated from Sphaerophysa salsula samples from Alashan of Inner Mongolia to investigate whether endophytic fungi exist in this plant and to assess the diversity and distribution of endophytic fungi. The optimal method for sterilization of plant materials surface with 75% ethanol and 2% NaClO was determined by the general method of endophytic fungus' isolation and purification, species and genus of endophytic fungus was identified by the traditional morphology and molecular biology. It was found that 75% enthanol for 30 s, 2% NaClO for 3. 5 min. and 75% enthanol for 50 s, 2% NaClO for 4 min. were more suitable for leaf and seed sterilization of Sphaerophysa salsula , respectively. Under the optimal surface sterilization conditions, leaf had a maximum isolation rates (41. 67%), followed with seed (37. 14%); and the species and the quantity ratio (38. 75%) of endophytic fungi isolated from seed was the highest, followed with stem (20. 00%). Eighty strains of endophytic fungi were isolated from 4 different tissues of Sphaerophysa salsula , which belonged to 10 genera, 6 families, 5 orders and 4 classes. Alternaria sp and Fusarium sp were the dominant species in this plant with the relative frequency 53. 75% and 21. 25%, respectively. There was an obviously difference in quantity, species and distribution of the endophytic fungi between different parts of Sphaerophysa salsula. Seed and leaf were the most vulnerable to infection and colonization by the endophytic fungi and the diversity was maximum in seed of Sphaerophysa salsula.%为探明苦马豆中是否存在内生真菌及其分布情况,对采自内蒙古阿拉善盟草原的苦马豆样品进行内生真菌分离.通过内生真菌常规分离纯化法分离内生真菌,以确定75％乙醇和2％NaClO的最佳表面消毒时间,并运用形态学方法和rDNA-ITS系列技术对分离菌株进行种属鉴定.结果显示苦马豆叶和种子用75％乙醇及2％ Na-ClO的最佳表面消毒时间分别为30 s、3.5 min和50 s、4 min.最佳消毒条件下,叶的分离率最高(41.67％),种子次之(37.14％),种子中内生真菌种类与数量比最高(38.75％),其次是茎(20.00％).从苦马豆的4种组织中共分离得到80株内生真菌,分属于4纲、5目、6科、10属,其中链格孢属(Alternaria sp.)和镰刀菌属(Fusarium sp.)的总相对分离率分别为53.75％和21.25％,为苦马豆内生真菌的优势菌属.苦马豆内生真菌的数量、种属组成与分布存在明显组织差异性；其中种子和叶是内生真菌侵染和定植的主要部位,且种子内生真菌多样性最高.
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