The effect of fabric on air permeability was studied through the use of 04 fabrics with the same twill woven pattern but different materials (100% cotton, 100% polyester, Pe/co, CVC). Each fabric was selected 05 samples with different fabric structure parameters, provided by local manufacturers for testing. The fabric samples were experimentally conducted to determinine the density of fibers, the fabric composition and fabric weight (g/m2 ). The fabric samples after determining the structural parameters were measured for air permeability on the Air Permeability Tester. The research results show that: Increasing density of fibers reduces the air permeability of fabric; the percentage of cotton yarn increases, the air permeability of fabric also increases; the weight of fabric (g/m2 ) also effects the air permeability of fabric.