We investigated Angelica dahurica (Fisch.) Benth. ＆ Hook. var. formosana (Boiss.) Yen by Transect Counts and Global Positioning System（GPS）once every week in Yangmingshan National Park Tatun mountains from January 2007 to December 2007. And we investigated the life cycle and distribution of Angelica dahurica; and further, we investigated the species of insects in the life cycle of Angelica dahurica. At last we analyzed the relation of insects and Angelica dahurica. The results showed that the life cycle of Angelica dahurica corresponded with the description by Zheng (2000). Angelica dahurica distributed affluently at the side of the traffic lane. The distribution of Angelica dahurica were crowded in summit. Angelica dahurica grew in different transect lines that the timber were abundant or sparse would influence the quantity and species of insects. Results showed that 113 species of insects were collected in the life cycle of Angelica dahurica. And the life cycle of Angelica dahurica could influence the quantity and species of insects. Particularly, it attracted many insects in anthesis. So, Angelica dahurica was nectar plant.