Thrips tabaci Lindeman is a serious pest of cucumber and onion in field and greenhouse conditions in Iran. Neoseiulus barkeri Hughes is an indigenous biological control agent in west of Iran on cucumber and maize that preys on spider mites and T. tabaci and can prevent the outbreak of them. In this study, the demographic parameters of the Iranian population of N. barkeri were determined using 1^st instar larvae of T. tabaci as prey under laboratory conditions at 30±1°C,65±5% RH and photoperiod 8:16 h (D:L). The results showed that N. barkeri successfully developed on 1^st instars larvae of T. tabaci. The developmental times for egg, larva, protonymph, deutonymph and all immature stages were 1.37, 1.03, 1.54, 1.71 and 5.68 days, respectively. Also, 96.66% of eggs hatched and the survival rate for the movable immature stages were 100%. Total prey consumption by protonymphs, deutonymphs and adult female was 2.70, 3.57 and 75.85 individuals, respectively. Adult longevity of the male was recorded as 14.36 days while the females lived longer (20.17 days). The female ratio was 0.62%. The intrinsic rate of increase (r_m) and the net reproductive rate (R₀) were 0.252 day^-1 and 18.70 female offspring, respectively. Our results showed that N. barkeri could be considered as a biological agent for the control of T. tabaci on cucumber. Expanding knowledge on the biological parameters of this predatory mite can help to increase the use of this indigenous biological agent for the control of T. tabaci on cucumber.