Abstract: Predation of Misumenopos tricuspidatus on mirids,Apolygus lucorum and Adelphocoris lineolatus was investigated in the laboratory.The spider began to prey on the nymph and adult mirids at the second instar,and the functional responses for adult spiders fitted well with HollingⅡtype.The daily maximum predatory capacity of the adult spider for the 2nd and 4th instar nymphs reached 56.5,22.1 for Ap.lucorum and 30.4,9.3 for Ad.lineolatus, respectively. The spider showed no preference between the two mirids species,but preferred larger individuals.Environmental temperature influenced predatory efficiency of the spider,with the optimum range of temperature being 20-35℃and predatory capacity of the adults decreasing drastically at temperature below 10℃.In cotton field,population dynamics of the mirids correlated well with that of the spider in 2007.It is concluded that the spider is an important natural enemy of the two mirids.