Abstract: Bidens pilosa L. is an invasive alien weed. The effects of temperature and illumination on seed germination of B. pilosa and changes of germination capacity during its storage under different temperature were studied. The results showed that illumination and natural temperature fluctuations are not necessary for its seed germination. Under the conditions of constant temperature from 15 to 30℃, the germination percentages reached above 80%, but under constant 35℃, seed germination was greatly restrained to a very low level and the seeds germinated could not complete their development into seedlings as well. There was nearly no difference in germination percentage between fresh seeds (97.7%) and seeds stored at -10℃ and 4℃ for 6 months (their germination percentages were 95% and 94.7%, respectively). As for the seeds stored at room temperature for 6 months, the germination rate decreased gradually and the sprouted seeds could not develop normally.