Abstract: A investigation on the arthropod community and its temporal niches was carried out in Brassica chinensis L. Fields from April to May, 2001. 22 species of arthropod were collected,of which there were 14 species of insect pests, 2 species of insect predators, 4 species of prositoids and two species of spiders. Plutella xylostella (Linnaeus), Phyllotreta striolata (Fabricius), Myzus persicae (Sulzer) and Liriomyza huidobrenisis (Blanchard) were the dominant insect pests. Paederus fuscipes Curtis, Cotesia plutellae Kurdjumov, Aphidius avenae Haliday, Erigondium grarminicolum (Sandevell) were the dominant nature emenies. The temporal niches of the dominant species were analyzed, the relationship between the dominant insect pests and nature enemies and the measures for nature enemy protection were discussed.