Athetis lepigone (Möschler) (Lepidoptera: Noctuidae) is an important insect pest of corn crops in China. To determine the effect of temperature on A. lepigone growth, and to provide a forecasting model for this pest, the development and fecundity of A. lepigone under five different temperatures (18, 21, 24, 27, 30 °C) was investigated, and an experimental population life table was constructed based on the obtained results. The results showed that the duration of development of A. lepigone decreased as the temperature increased from 18 to 30 °C. Approximately 95% of mature larvae stopped pupating at 18 °C, and about 70% of mature larvae stopped pupating at 21 °C. When the growth chamber temperature was above 24 °C, no growth arrest was observed. The results indicated that the optimum growth temperature of A. lepigone was about 26.47 °C. In this study, the highest survival rate, fecundity per female, and population index trend were observed when the temperature was set at 27 °C. The percentages of larvae that could spin cocoons after the 5th or 6th instar differed at the different temperatures. The developmental threshold temperatures for A. lepigone eggs, larvae, pre-pupae, pupae, preoviposition females, and the whole generation (i.e., egg to oviposition) were 11.03, 9.04, 15.08, 11.79, 11.63, and 10.84 °C, respectively, and their effective accumulative temperatures were 63.51, 339.42, 30.04, 118.41, 35.06 and 574.08 degree-days, respectively. Based on the effective accumulative temperature law, this pest insect can have four generations in most of the Huang-Huai region of China, and two to three generations annually in some cold regions. Athetis lepigone may have four generations in the mid-southern part of Hebei Province. This prediction matches the field survey results.