[Objectives]  To investigate the potential of using the fungus Beauveria bassiana to protect maize crops from Spodoptera  frugiperda, a polyphagous, important, invasive, insect pest, that poses a major threat to agriculture in China. [Methods]  The Beauveria bassiana Bb378 strain, which is highly pathogenic to S. frugiperda, was isolated and 3rd instar S. frugiperda larvae were inoculated with a 0.05% Tween-80 aqueous solution containing either 1 × 10⁴, 1 × 10⁵, 1 × 10⁶, 1 × 10⁷, or 1 × 10⁸ conidia/mL of B. bassiana spore suspension. The infection rate and number of dead larvae were observed and recorded after 3, 7 and 14 days. Effects of the Bb378 strain on the feeding of S. frugiperda on maize were studied by using the seed soaking, root irrigation and foliar spraying methods. [Results]  After 14 days the cumulative corrected mortality and LC₅₀ of the highly pathogenic Bb378strain were 48.61% and 1.11 × 10⁸ conidia/mL, respectively. Spraying the Bb378 strain onto maize foliage increased the leaf area and fresh weight of corn, whereas root irrigation and seed soaking had an obvious  effect on plant height. The growth promoting effect of the Bb378 strain was obvious at concentrations of 1×10⁷ and 1×10⁸ conidia/mL. Soaking seeds in suspensions of 1×10⁷ and 1×10⁸ conidia/mL significantly repelled newly hatched and 3rd instar larvae. Irrigating roots with suspensions of 1×10⁷ and 1×10⁸ conidia/mL also had an obvious repellent effect on newly hatched larvae, but only a concentration of 1×10⁸ conidia/mL significantly repelled 3rd instar larvae. There was, however, no significant difference between leaf spraying and the control. [Conclusion]  The Bb378 strain is highly pathogenic to S. frugiperda. Applying B. bassiana to maize not only promoted plant growth, but also inhibited the feeding behavior of S. frugiperda, findings that justify further research and development.