The survival, development, fecundity and even population expansion of insects are all affected significantly by extremely high temperature. The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the most important and destructive pest of brassicaceae plants in the world. Among lepidopterous, this pest has shown the highest resistant to chemical pesticide. In this research, the effect of heat shock on pupa stage of Plutella xylostella and its development, adult longevity and fecundity were studied at laboratory condition (25 ºC, 65±70 % RH and a photoperiod of 16:8 (L: D) h) on Brassica napus. Diamondback moth pupa were exposed to 30, 35 and 40 ºC for duration of 2, 4, 6 and 8h and then returned to normal temperature condition (25 ºC). The pupa maintained at 25 ºC were used as untreated control. The result showed that the pupal development time were significantly affected after heat shock (30 to 40ºC) in comparison with control (25 ºC). The pupal development stage was shortest (3±0.08 days) at 35ºC for 8h. Heat shock temperature was also significantly affected adult longevity and fecundity of diamondback moth. The adult longevity of female (11.20±1.10 days) and male (11.23±0.89 days) were highest at 30 ºC for 8h, respectively. The fecundity of females was significantly affected by at heat shock temperatures in comparison with control. The lowest of fecundity was obtained at 30 ºC for 6h. Our findings can be used to develop a more profound understanding on the potential for this insect to evolve in response to environmental temperature changes.