An economical pretreatment method is needed to produce the L-lactic acid from renewable biomass. Six different combinatorial experiments including choline chloride [Ch][Cl], 1-ethyl-3-methylimidazolium chloride [Emim][Cl], and 1-butyl-3-methylimidazolium chloride [Bmim][Cl], diluted acid sulfuric acid (DSA), and two ionic liquids (ILs) were tested. Ionic liquid (ILs) step performed at 90, 110, and 130 °C. The cellulose content of sugarcane bagasse (SCB) increased from 42.1 % (raw material) to 74.6 % (combinatorial pretreatment with DSA and [Emim][Cl]) to 79.9 % (after water washing). Pretreated SCB was employed in enzymatic saccharification and L-lactic acid fermentation. Enzymatic hydrolysis resulted in the maximal levels of glucose titer (220.7 g/L) and yield (73.5 %). L-lactic acid concentration reached to 204.1 g/L when SCB fermented with Lactobacillus casei ATCC 334 at a 25 % w/w solid loading. The two-step pretreatment SCB underwent morphological changes, as evidenced by FTIR, XRD, and SEM analyses. High cellulose levels and high lactic acid highlight the advantages on energy efficiency of a two-step combined pretreatment procedure over a standard single-step pretreatment technique.