Abstract: 【Objective】 To analyze the effects of Pennisetum purpureum on development， reproduction， and flight capacity of Spodoptera frugiperda， which could provide theoretical basis for the regional precision management of Spodoptera frugiperda in southern China. 【Method】 Two groups of Spodoptera frugiperda were established and reared on Pennisetum purpureum and Zea mays respectively. The age-stage life table for both sexes was constructed for each group， and the tethered flight mill technique was employed to measure adult flight capacity. Biological characteristics were systematically compared between Spodoptera frugiperda on Pennisetum purpureum and Zea mays groups. 【Result】 Compared with the Zea mays group， the developmental duration of each larval stage in the Pennisetum purpureum group was significantly prolonged （P<0.05， the same below）， the preadult duration was extended by 7.73 d， and 28% of individuals exhibited an increased number of larval instars. The age-stage specific survival rate curve revealed that the survival rate of Pennisetum purpureum group declined sharply after the 2^nd instar. Furthermore， the oviposition period and adult longevity of both sexes were significantly shortened in Pennisetum purpureum group. The intrinsic increase rate （0.12）， net reproductive rate （123.84）， and finite increase rate （1.13） were low， and mean generation time was prolonged by 10.47 d， indicating that Spodoptera frugiperda on Pennisetum purpureum group required a longer duration to complete one generation. However， no significant differences were observed in Spodoptera frugiperda pupal weight， fecundity per female， or flight distance， flight duration， and mean flight speed of male and female adults between the two host groups （P > 0.05）. These results suggested that although Pennisetum purpureum is a low-suitable host for Spodoptera frugiperda， it did not impair the flight capacity of adult moths. 【Conclusion】 Pennisetum purpureum is not an optimal host for Spodoptera frugiperda and is unfavorable for rapid population growth， yet it does not diminish the migratory capacity of adults. In the absence of Zea mays， Pennisetum purpureum can still support the establishment and development of Spodoptera frugiperda populations， thereby facilitating migratory dispersal. It is recommended to monitor Spodoptera frugiperda populations on alternative hosts such as Pennisetum purpureum during the non-growing season of Zea mays， and to suppress over-summering and over-wintering source populations through mowing or removal to reduce the risk of damage to the subsequent maize crop.