The objective of this study was to use statistically based experimental designs for the optimization of xylanase production from Alternaria mali ND-16. Ten components in the medium were screened for nutritional requirements. Three nutritional components, including NH₄Cl, urea, and MgSO₄, were identified to significantly affect the xylanase production by using the Plackett–Burman experimental design. These three major components were subsequently optimized using the Doehlert experimental design. By using response surface methodology and canonical analysis, the optimal concentrations for xylanase production were: NH₄Cl 11.34 g L⁻¹, urea 1.26 g L⁻¹, and MgSO₄ 0.98 g L⁻¹. Under these optimal conditions, the xylanase activity from A. mali ND-16 reached 30.35 U mL⁻¹. Verification of the optimization showed that xylanase production of 31.26 U mL⁻¹ was achieved.