Effects of elevated atmospheric CO 2 (elevated CO 2 vs. ambient CO 2 ) and temperature (+0.67-0.79°C vs. ambient temperature) on the developmental life cycle of Spodoptera litura and the food utilization of the fourth-instar larvae fed on soybean (resistant cultivar Lamar vs. susceptible landrace JLNMH) grown in open-top chambers were studied from 2013 to 2015. The results indicated that: (i) compared with ambient CO 2 , elevated CO 2 significantly prolonged the duration of larva and pupa, and adult longevity; significantly decreased the pupation rate, pupal weight, fecundity, the relative growth rate (RGR), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD); and increased the relative consumption rate (RCR) and approximate digestibility (AD). (ii) Compared with ambient temperature, elevated temperature significantly shortened the duration of larva and pupa; significantly decreased the pupal weight; and increased the RGR, RCR, ECD and ECI. (iii) Compared with the susceptible soybean accession JLNMH, the resistant soybean cultivar Lamar significantly prolonged the duration of larva and pupa; significantly decreased the pupation rate, pupal weight, adult longevity, fecundity and RGR, RCR and AD; and increased the indexes of ECD.