Electronic doped quantum dots (Ed-QDs), by heterovalent cations doping, have held promise for future device concepts in optoelectronic and spin-based technologies due to their broadband Stokes-shifted luminescence, enhanced electrical transport and tailored magnetic behavior. Considering their scale-up requirement and the low yielding of several current colloidal synthesis methods, a stable and efficient bulk synthesis strategy must be developed. Microreactors have long been recognized as an effective platform for producing nanomaterials and fabricating large-scale structures. Here, we chose microreactor platform for continuous synthesis of Ed-QDs in the air at low temperatures. By original reverse cation exchange reaction mechanism together with varying the kinetic conditions of microreactor platform, such as liquid flow rate, the Ag doped CdS (CdS:Ag) Ed-QDs with higher yield have been synthesized successfully due to the continuous synthesis advantages with a high degree of size selectivity. Enabled by microreactor engineering simulation, this research not only provides a new synthetic method towards scale-up production but also enables to improve chemical mass production of similar functional QDs for optical devices, bio-imaging and innovative information processing applications.