A lignocellulose liquid hot water (LHW) pretreatment process was strengthened by the direct recycling of spent liquor. The use of rich "spent liquor and its byproduct acetic acid was proposed as a method of strengthening LHW pretreatments, which, can reduce energy consumption while producing less wastewater. The results showed that the glucose yield increased from 80.82% to 85.44% during enzymatic hydrolysis after the spent liquor had been recycled three times, at which point the acetic acid content was 8.1 g/L. When the spent liquor was reused three times, the furfural and 5-hydroxymethyl furfural (HMF) concentrations in the pretreatment liquid were 1.95 and 0.96 g/L, respectively. These levels are lower than the levels that significantly inhibit the growth of fermenting microorganisms. Furthermore, experiments were conducted with acetic acid contents between 0 and 40 g/L to investigate the difference between the acetic acid-catalyzed LHW pretreatment and the recycled spent liquor LHW pretreatment. The optimum concentration of acetic acid was 10 g/L, which confirmed the feasibility of using recycled spent liquor to strengthen the LHW pretreatment. Surfactant was also added during enzymatic hydrolysis to strengthen the LHW pretreatment process. The glucose yield of corn stover pretreated with recycled spent liquor increased to 89.84% with the addition of Tween.80.