The effects of four Culture medium on the symbiosis of different varieties of soybean and AM fungi (Rhizophagus irregularis) were studied by pot culture. The difference between black ink and trypan blue staining methods and the application of the magnified grid line and the five-class methods in mycorrhizal symbiosis structures detection were also compared in this research.The results show that vermiculite and soil (V: V = 4: 1) are more conducive to the infection of AM fungi with soybean. The arbuscular abundance, hypha density and vesicle abundance in this culture substrate are significant higher than others, so it can be used as the best culture substrates for soybean and AM fungi symbiosis. For large-scale mycorrhizal symbiosis structures detection, ink staining and the magnified grid line method are the best methods in currently.