Cellulase represents a major cost for biochemical conversion of lignocellulosic biomass to biofuels. In the present study, in-house production of cellulases from Ammonia Fiber Expansion pretreated corn stover (AFEX-CS) using Trichoderma reesei Rut C-30 was investigated. Seed culture was conducted in a simple medium containing corn steep liquor (CSL) and AFEX-CS hydrolysate. The effects of fermentation medium components (CSL, AFEX-CS, Tween 80 and CaCO3) on cellulase production were investigated and a simple fermentation medium was developed containing 20 g L−1 AFEX-CS and 4.0 g L−1 CaCO3. A cellulase activity of 1.5 FPU per mL was produced in this medium. Addition of 0.5% (v/v) CSL in the fermentation medium further improved cellulase activity (1.9 FPU per mL). Enzymatic hydrolysis of AFEX-CS using in-house produced enzymes generated high sugar yields with high enzyme loading. Proteomics analyses indicated that EGI and CBHII were deficient in the in-house produced enzyme cocktail when compared to the optimal cocktail for hydrolyzing AFEX-CS.