This study develops low-fat microwaved peanut snacks (LMPS) using partially defatted peanuts (PDP) with different defatting ratios, catering to people’s pursuit of healthy, low-fat cuisine. The effects of defatting treatment on the structural characteristics, texture, color, and nutrient composition of LMPS were comprehensively explored. The structural characteristics of LMPS were characterized using X-ray micro-computed tomography (Micro-CT) and scanning electron microscope (SEM). The results demonstrated that the porosity, pore number, pore volume, brightness, brittleness, protein content, and total sugar content of LMPS all significantly increased (P<0.05) with the increase in the defatting ratio. At the micro level, porous structure, cell wall rupture, and loss of intracellular material could be observed in LMPS after defatting treatments. LMPS made from PDP with a defatting ratio of 64.44% had the highest internal pore structural parameters (porosity 59%, pore number 85.3×105, pore volume 68.23 mm3), the brightest color (L* 78.39±0.39), the best brittleness (3.64±0.21) mm–1), and the best nutrition (high protein content, (34.02±0.38)%; high total sugar content, (17.45±0.59)%; low-fat content, (27.58±0.85)%). The study provides a theoretical basis for the quality improvement of LMPS.