High content of lignocellulosic substrate enzymatic hydrolysis have the advantages of low equipment cost, saving water and energy consumption, etc. In order to study the influence of different pretreatment methods based on alkali, with high solids loading of sugarcane bagasse (SCB) was used as raw material, NaOH, alkaline ethanol and alkaline hydrogen peroxide (AHP) were selected as pretreatment chemicals, respectively, which was used to optimize the pretreatment and enzymatic hydrolysis. The solid-liquid ratio of each group was set as 2%, 10%, and 20% (w/v) for the enzymatic hydrolysis efficiency comparison. The field emission scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to analyse the morphology and crystallinity of the substrates. After optimization, the glucan recovery and lignin removal of the different pretreatment method with 2% NaOH, 2% NaOH + 40% ethanol and 2% NaOH + 4% H2O2 were 91.19%, 96.63%, 95.38% and 78.02, %, 83.16% 98.54%, respectively. Although the glucan conversion rate after enzymatic hydrolysis was inversely proportional to the solid content, the influence degree of each pretreatment method was different. The SCB pretreated by AHP for high solids saccharification showed the highest yields. Keep 20% (w/v) of substrate for 72 h, 84.06% of glucan conversion rate was achieved. When the final solid content increased to 36% (w/v), the enzymatic hydrolysis conversion of glucose and xylose concentration at 144 hours were 214.37 g/L and 74.88%, respectively. The high glucan conversion rate indicates that pretreatment with AHP is an excellent method for enzymatic hydrolysis of high solids content of lignocellulosic biomass.