【Aim】 This study aimed to utilize entomopathogenic nematodes (EPNs) against Spodoptera frugiperda in maize fields. 【Method】Four different EPN strains were screened, and in laboratory, their toxicity, lethal times, and dosages were determined on the 3rd and 6th instar larvae of S. frugiperda. The effective control dosage and field effectiveness were tested by spraying the nematodes into corn bell mouth at 6-8 leaf stage after sunset. 【Result】 The lethal concentrations (LC₅₀) of Steinernema feltiae SN, Heterorhabditis bacteriophora H06, Heterorhabditis beicherriana Cherry and Oscheius chongmingensis Tumian to the 3rd instar larvae of S. frugiperda after 72 h were 22.13, 36.54, 60.01 and 1369.40 IJs·larva^-1, respectively, and those on the 6th instar larvae after 72 h were 18.67, 31.25, 45.52 and 897.28 IJs·larvae^-1, respectively. The optimal number of infective hours for SN, H06, Cherry, and Tumian was 72 h, and their optimal lethal dosage was 100 IJs·larva^-1 (except for Tumian which the optimal lethal dose was 900 IJs·larvae^-1). The best field application dosage was 70,000 IJs·plant^-1, at which the corrected control effect was 65.80% after 16 d of spraying. 【Conclusion】 Among the tested strains, SN had the strongest pathogenicity and the greatest potential as a biological control agent against S. frugiperda in the field. The nematode spraying in corn fields has the best control effect at the stage of 6-8 leaves and the 3rd larval instar.