This study was carried out to investigate the effect of the photoperiod and temperature on the reproductive diapause in Orius strigicollis. The photoperiod and temperature affected nymphal development, adult longevity, diapause induction, and diapause termination in O. strigicollis. At $18^{circ}C$, nymphs developed significantly faster at a photoperiod of 8:16 (L:D) h than at a 12:12 (L:D) h. When kept at $15^{circ}C$ and 9:15 (L:D) h continuously from the $2^{nd}$ instars, the longevity of adult O. strigicollis was much shorter than that from the $4^{th}$ instars, but their longevity was not different between the genders. At $18^{circ}C$, when continuously kept under short photoperiod from the first three nymph stages, $100\%$ of adults entered the reproductive diapause within 40 days after adult eclosion. From the $1^{st}$ to $3^{rd}$ instars, O. strigicollis displayed a long-day response with a critical photoperiod between 12 h and 14 h at $18^{circ}C$ within 20 days after adult eclosion. When continuously kept at $15^{circ}C$ and $18^{circ}C$ with a 9:15 (L:D) h photoregime from the 2nd instars, all females entered the reproductive diapasue, while the diapause incidence at $20^{circ}C$ and $25^{circ}C$ was quite low even within 20 days after adult eclosion. No diapause incidence was found when only the egg or the first three nymph stages were kept at $18^{circ}C$ and 8: 16 (L:D) h, while the later two nymph stages showed a slight increase in diapause incidence. Combined exposure from the nymph to adult stages to $18^{circ}C$ and 8:16 (L:D) h is necessary to attain $100\%$ of diapause incidence. Diapause in O. strigicollis was terminated rapidly as long photoperiod and/or lower temperature was treated.