Dielectric Si3N4 nano-pillar arrays (NPA) are designed for the broad infrared waveband antireflection applications. The Wood-Rayleigh anomaly diffraction and Mie-type scattering (M − S) resonance characteristics of the NPA nanophotonic structures are analyzed, which show the excellent optical performances. M − S resonance can be broadened by high-index semiconductor substrate and the interactions between nanopillars, which resulting the expected ultra-low light reflection at the broad infrared waveband. The orderly and uniformly large area Si3N4 NPAs are successfully fabricated by low-cost nanosphere lithography, and the measured infrared light reflection spectrums are fit well with the theoretical results. For the GaSb TPV cell with the emitter temperature of 1200 °C, the ultralow flux-spectrum-weighted reflection of ∼1.72 % is obtained with the fabricated Si3N4 NPA, which demonstrate great potential for infrared optoelectronic applications.