A facile strategy is reported in this study to synthesize bifunctional porous polymers bearing boronic and sulfonic acids as a new type of cellulase-mimetic solid acids for cellulose hydrolysis in water. The boronic acid and sulfonic acid groups of the solid acids mimicked the cellulose-binding domains and the cellulose-hydrolytic domains of cellulase, respectively. As expected, the cellulase-mimetic solid acids were able to hydrolyze microcrystalline cellulose (Avicel) to glucose effectively because of the synergic effect between the boronic and sulfonic groups. For example, the solid acid synthesized from naphthalene-1-boronic acid at 120 °C was able to hydrolyze Avicel to glucose by 42.7% at 24 h and 94.6% at 48 h, respectively. If the Avicel was ball-milled for 2 h, it could be hydrolyzed by 94.9% within 24 h at 120 °C.