The developmental time of immature stages of Paromius exiguus (Distant) was investigated at nine constant temperatures (15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, $35{pm}1^{circ}C$), 20-30% RH, and a photoperiod of 14:10h (L:D). Eggs did not develop at $15^{circ}C$, and their developmental time decreased with increasing temperatures. Its developmental time was longest at $17.5^{circ}C$ (28.2 days) and shortest at $35^{circ}C$ (5.9 days). The first nymphs failed to reach the next nymphal stage at 17.5 and $35^{circ}C$. Nymphal developmental time decreased with increasing temperatures between $20^{circ}C$ and $32.5^{circ}C$, and developmental rate was decreased at temperatures above $30^{circ}C$ in all stages except for the fourth nymphal stage. The relationship between developmental rate and temperature fit a linear model and three nonlinear models (Briere 1, Lactin 2, and Logan 6). The lower threshold temperature of egg and total nymphal stage was $l3.8^{circ}C$ and $15.3^{circ}C$, respectively. The thermal constant required to reach complete egg and the total nymphal stage was 109.9 and 312.5DD, respectively. The Logan-6 model was best fitted ($r^2$=0.94-0.99), among three nonlinear models. The distribution of completion of each development stage was well described by the 3-parameter Weibull function ($r^2$=0.91-0.99).