Fast jet mixing plays an important role in the intensification of precipitation process. In this work, the precipitation of barium sulfate in a multi-orifice-impinging transverse (MOLT) jet reactor was studied experimentally and numerically. RANS approach coupled with population balance equation (PBE) model was used to predict the process. Large scale variance and small scale variance were solved to evaluate the effect of macromixing and micromixing on the precipitation process, respectively. The influence of Reynolds number (Re-M), initial feeding concentration of reactants (C-0), and the scale-up of the jet reactor, on the distribution of supersaturation ratio, nucleation rate and crystal growth rate was discussed. The precipitation process can be intensified (here referring to producing smaller nanoparticles with narrower particle size distribution) by increasing ReM at lower ReM region or when the jet reactor is scaled up, or by increasing C-0 when C-0 is less than 0.4 kmol/m(3). (C) 2017 Elsevier B.V. All rights reserved.