FeNi-based alloy layer was coated on High manganese steel surface by plasma cladding technology, Analysis of the microstructure of inter-metallic compounds of aging temperature change and its effect on the impact toughness. The experimental results indicated that the microstructure of the coating Layer after 300-600 tempering was characterized by martensite and retained austenite. As the aging temperature increased, the impact toughness initially increased and then decreased; The inter-metallic compounds after 300 and 400 tempering are distributed on the original martensite boundaries, impact toughness was 66 J / cm2 and 109 J / cm2 ; after 500 ℃ quenching precipitation between spherical metal compound, and the formation of reverted austenite, impact toughness peak 182 J / cm2; 600 ℃ aging precipitates thick, impact toughness of 114J / cm2. The morphology and distribution of inter-metallic compounds is the key factor that influences the impact toughness of coating Layer.