A　four-stage　oscillating　feedback　millireactor　with　splitters　(S-OFM)　was　designed　to　improve　the　mixing　performance　based　on　chaotic　advection.　Three-dimensional　CFD　simulations　were　used　to　investigate　its　flow　characteristics　and　mixing　performance,　and　the　generation　mechanisms　of　secondary　flows　were　examined.　The　results　show　that　the　mixing　index　(MIcup)　increased　with　the　increase　in　the　Reynolds　number　(Re),　and　MIcupcould　reach　99.8%　at　Re　=　663.　Poincaré　mapping　and　Kolmogorov　entropy　were　adopted　to　characterize　the　chaotic　advection　intensity,　which　indicates　that　there　is　a　intensity　increase　with　the　increase　in　Re.　In　addition,　the　results　of　Villermaux-Dushman　experiments　demonstrate　that　S-OFM　performs　excellently,　and　the　mixing　time　could　reach　1.04　ms　at　Re　=　2764.　Finally,　S-OFM　was　successfully　used　to　synthesize　CdS　nanoparticles　with　cubic　hexagonal　phase　junctions.　At　a　flow　rate　of　180　mL/min,　the　average　particle　size　was　10.5　nm　and　the　particle　size　distribution　was　narrow　(with　a　coefficient　of　variation　of　0.14).　©　2022　American　Chemical　Society.　All　rights　reserved.