The　special　and　unique　role　of　the　spacer　of　Gemini　surfactant　in　self-assembly　is　reviewed,　which　is　considered　to　benefit　mainly　from　both　the　spacer　length　and　the　rigid/flexible　features.　These　two　effects　lead　to　the　synergism　of　two　alkyl　tails　of　a　Gemini　molecule,　the　change　in　the　charge　density　of　its　headgroups,　the　variation　of　its　molecule　geometry　by　which　rich　structures　and　morphologies　of　aggregates　yield,　etc.　More　detailed,　the　flexible　spacer　influences　the　above　functions　of　the　Gemini　mainly　depending　on　its　length.　Too　long　flexible　spacer　can　bend　toward　the　alkyl　tails　so　as　to　meet　the　chemical　environment　around　the　molecule,　by　which　the　molecule　self-assembly　is　influenced.　The　effect　of　the　short　rigid　spacer　is　almost　identical　with　that　of　the　flexible　spacer　having　a　similar　length.　However,　the　long　rigid　spacer　yields　quite　different　effects　from　the　flexible　spacer　owing　to　the　two　alkyl　tails　are　inhibited　to　be　close,　which　leads　to　the　column-like　molecular　shape　and　the　identical　probability　for　the　cis/trans　configuration　of　the　two　alkyl　tails　around　the　spacer.　These　make　the　Geminis　with　long　rigid　spacer　form　network-like　aggregates　at　low　concentrations,　which　can　be　transformed　into　threadlike　micelles　or　vesicles　with　low　surface　curvature　with　increasing　the　Gemini　concentration　or　adding　a　few　additives.　Under　suitable　conditions,　a　few　molecules　in　the　aggregates　can　be　hastened　to　yield　trans-form,　resulting　in　the　cohesion　between　the　aggregates　through　the　hydrophobic　interactions　between　the　extended　alkyl　tails.　The　chemical　modification　for　the　spacer　is　also　discussed,　which　is　expected　to　promote　molecular　self-assembly,　or　give　some　new　functions　to　the　aggregates.　The　cases　listed　here　well　indicate　the　specialty　and　uniqueness　of　the　Gemini-structure　of　molecule　and　impress　us　for　the　complicated　self-assembly　behavior　and　diversified　aggregates　of　Gemini　surfactants.