In this study,the optimal component of liquid medium for in vitro germination of dried mature pollen of Eucommia ulmoides Oliv.was screened and the characteristics of pollen germination and microfilament distribution of pollen tube were investigated.The results were as follows:(1)The optimal liquid medium for pollen germination contained 200 g/L sucrose,30 mg/L boron acid and 10 mg/L calcium nitrate.The germination rate reached 46.29%±3.75% after incubating at 26 ℃ for 18 hours.(2)Under the optimal culture condition,germination rate increased sharply within 6 hours,and then stably.The tubes grew very fast within 8 hours,and then decreased the speed of elongation.After 48 h culturing,the length of tubes could reach 363.14±30.51 μm.(3)The pollen grains of E.ulmoides were two-celled.During the germination,the vegetative nucleus usually enters into the tube ahead of the generative nucleus.The mitosis of generative nucleus took place in the pollen tube,and the mitotic behavior can be observed gradually after 12 hours incubation in the liquid medium.(4)Microfilament bundles which formed during pollen germination paralleled to the direction of tube elongation.The bundled microfilaments formed a continuous system together with arrays of microfilament networks to move the nuclei in the tube.