ABSTRACT Multifeature (MF) design is a potential approach for the secondary design of microchannel heat sinks (MHSs). In this paper, turning microchannels with variable cross sections (TM‐VC) were designed. The effects of different coupling methods on the convective heat transfer performance were studied. The results revealed that MF designs can effectively enhance heat transfer performance. Under the same pumping power consumption, compared with that of single‐feature microchannels and traditional straight microchannels, the heat transfer performance of turning microchannels with inner ribs and outer cavities (TM‐OCIR) increased the most—up to 19.3% and 35%, respectively. The local entransy theory was also employed to analyze and elucidate the heat transfer mechanism of the TM‐VC. The results showed that the turning effect can enhance the inner rib effect, leading to lower entransy dissipation and higher entransy gain (EG), thus achieving higher convective heat transfer efficiency.