We　report　a　systematic　investigation　on　the　mixed　micellization　of　the　binary　homologues　of　Gemini　surfactant　12-s-12　series　that　has　a　flexible　polyethylene　spacer.　The　results　showed　that　the　micellization　behavior　deviates　from　the　ideality　when　the　difference　of　the　spacer　lengths　(Delta　s)　of　two　components　is　larger　than　6.　The　obvious　synergism　between　two　components　occurs　in　the　mixtures　of　12-2-12/12-18-12　and　12-4-12/12-18-12.　This　was　attributed　to　a　relatively　large　difference　in　the　molecular　shape　of　the　two　components　induced　by　the　length　and　the　configuration　of　the　spacer　chain,　which　yielded　better　steric　compensation　between　two　components　within　a　mixed　micelle　than　other　mixed　systems.