A　micro　stereovision　system　with　a　stereo　light　microscope　(SLM)　has　been　applied　in　micromanipulation　systems.　There　is　a　coupling　connection　between　two　optical　paths　of　a　stereo　light　microscope.　The　coupling　intension　corresponds　with　two　factors:　the　structure　of　an　SLM　and　the　position　of　an　object　point　in　the　view　of　an　SLM.　In　this　paper,　a　correlation　function　is　proposed　to　describe　the　coupling　intension　between　the　couple　optical　paths　of　an　SLM.　The　quantified　results　are　applied　to　the　error　analysis　of　the　imaging　model.　Experiments　show　that　the　correlation　of　the　optical　paths　of　a　common　main　objective　of　stereo　light　microscope　(CMO-SLM)　is　little　more　than　that　of　a　G-SLM,　and　the　error　must　be　considered　when　a　pinhole　imaging　model　is　used　to　analyze　its　correlation.　©　2007　Higher　Education　Press　and　Springer-Verlag.