Development of the Fall Armyworm Spodoptera frugiperda (J.E. Smith) was studied on constant temperatures (15, 20, 25, 30 and 35 ̊C ±1 ˚C), carried out in laboratory of Department Research Vegetable Pests at the Plant Protection Research Institute, Giza Governorate, during years 2021 and 2022. Development of immature stages was accelerated on tested temperatures. Total averaged of immature stages was 69.53±2.72, 52.93±1.43, 30.93±0.91, and 23.20±0.69 and 15.96±0.36 days at 15, 20, 25, 30 and 35˚C, respectively. Generation period ranged between 78.53±2.65 and 18.03±0.37 days at 15 and 35˚C, respectively. Additionally, adult female survived slightly longer than male and fecundity was decrease at temperature (15 ̊ C) than higher (30 ̊ C). Estimated the threshold of development (to) to be 11.14, 10.50, 10.90 and 10.81 ˚C for egg, larval, pupal, all immature and generation stages, respectively. Thermal requirements (D.D's) were 55.76, 225.50, 133.31, 414.05 and 472.21 heat units are required for completion the development of egg, larval, pupal, all immature and generation stages. Recorded the highest average numbers of eggs laid /female (Fecundity) and Hatching% (fertility) was 713.33±30.60 and Hatching% 98.13% at 30 ̊ C. whereas, the mortality% were 17.90 & 1.61 and 16.00 & 2.79 % for larval and pupal, respectively. Also, highest the percentage of emergence was 98.33 % at 30 ˚C, and lower the percentage of emergence was 77.78 % at 15 ˚C. The life table analysis indicted that doubling generation time (DT) was 15.06, 10.19, 5.09, 3.74 and 3.01 days at 15, 20, 25, 30 and 35˚C, respectively. Also, the percentage of survival was 2.08, 2.66, 6.70, 8.30 and 2.98 at 15, 20, 25, 30 and 35˚C, respectively.