Substrate reflectivity needs to be controled to reduce the impact of thin-film interference on lithography performance in hyper numerical aperture (NA) lithography. Based on thin film optics method, the control of substrate reflectivity with bottom antireflection coating (BARC) was investigated for hyper-NA lithography. Single-layer and dual-layer BARC on a silicon substrate were optimized to investigate the margins of BARC’s optical parameters which meet the requirements of hyper-NA lithography. It is found that single-layer BARC fails to control substrate reflectivity when NA is more than 0.8 and dual-layer BARCs become essential. The substrate reflectivity of TE wave is more uncontrollable as compared to TM wave. The optimized values of refractive index for single-layer BARC grow as the NA increases. In a dual-BARC structure, the top layer should be low absorptive while the bottom one should be high absorptive. It provides theory base for the research of BARC materials and the control of substrate reflectivity in hyper-NA lithography.