Improving the emission performance of colloidal quantum dots (QDs) is of paramount importance for their applica-tions on light-emitting diodes (LEDs),displays and lasers.A highly promising approach is to tune the carrier recombination channels and lifetime by exploiting the energy transfer process.However,to achieve this precise emission optimization,quantitative modulation on energy transfer efficiency is highly desirable but still challenging.Here,we demonstrate a con-venient approach to realize tunable energy transfer efficiency by forming QDs mixture with controllable donor/acceptor(D/A) ratio.With the mixing ratio ranging from 16/1 to 1/16,the energy transfer efficiency could be effectively tuned from near zero to ～ 70％.For the high mixing ratio of 16/1,acceptors obtain adequate energy supplied by closely surrounding donors,leading to ～ 2.4-fold PL enhancement.While for the low mixing ratio,the ultrafast and efficient energy extraction process directly suppresses the multi-exciton and Auger recombination in the donor,bringing about a higher threshold.The facile modulation of emission performance by controllably designed mixing ratio and quantitatively tunable energy transfer efficiency will facilitate QD-based optoelectronic and photovoltaic applications.