Reactivity is a critical parameter of dissolving pulp, which determines toxic chemical (i.e. carbon disulfide) consumption in rayon production. In this study, the depth refining was carried out to upgrade pre-hydrolysis kraft (PHK) pulp prior to cellulase treatment. The hypothesis is that the mechanical refining can not only increase reactivity by liberating additional hydroxyl groups, but also enhance cellulase efficiency by improving enzymatic accessibility. Results showed that the Fock reactivity of refined pulp (beating degree of 50°SR) was increased to 78.0 % from 54.8 % of the original (19°SR), which was mainly caused by inter- molecular hydrogen bond changes, supported by FTIR analysis. In addition, the cellulase adsorption ratio of refined pulp (30–50 °SR) was increased in a range of 39.7–71.2 %, which verified the improvement of enzymatic accessibility. As a result, the integrated process consisting of mechanical refining and cellulase treatment (at cellulase dosage of 0.5 mg/g pulp) yielded a much better result than the control (at cellulase dosage of 1 mg/g pulp) in terms of reactivity increase and viscosity decrease. Other pulp properties, such as fiber length and fines content, water retention value (WRV), specific surface area (SSA), crystallinity, and morphology, were all supported the positive effect of depth refining on activation of dissolving pulp during cellulase treatment.