Three representative types of simplified micromixers, namely, micromixer with simplified model of plan A (MSMA), the micromixer with simplified model of plan B (MSMB) and the micromixer with simplified model of plan C (MSMC), are designed according to the structure of topological micromixer with reversed flow (TMRF0.75), a novel micromixer presented by us in 2016. The flow and mixing mechanism of three micromixers are numerically investigated for a wide range of Reynolds numbers (Re): 0.01-100. The mixing performance and pressure drop of them are evaluated. MSMA, MSMB and MSMC have high mixing performance with mixing index all beyond 80% at all Re. Because of different structures, resulting in different intensities of mixing, the mixing indexes of MSMA and MSMC are even beyond 90% at all Re. At last, according to lots of fruitful numerical simulations and vast analytical data in the respects of the concentrations distributions, the velocity field and the pressure drop, it is specific to conclude that unlike our previous complex structure (TMRF0.75), MSMA, MSMB and MSMC are successful in reducing the difficulty of process, decreasing pressure drop and still keeping high mixing efficiently. (C) 2017 Elsevier Ltd. All rights reserved.