The　micro　Stereovision　systems　with　stereo　light　microscopes　(SLM)　have　been　applied　to　micromanipulation　systems.　There　is　a　coupling　connection　between　the　two　optical　paths　of　a　stereo　light　microscope.　The　coupling　intension　corresponds　with　two　factors.　The　first　one　is　the　structure　of　a　stereo　light　microscope,　and　the　second　is　the　position　of　a　random　object　point　in　the　view　field　of　a　stereo　light　microscope.　A　correlation　function　is　proposed　to　describe　the　coupling　intension　of　two　optical　paths　for　the　quantity　of　correlation　between　the　couple　optical　paths　of　a　stereo　light　microscope.　The　quantified　results　are　applied　to　the　error　analysis　of　an　imaging　model.　Experiments　show　that　correlation　of　optical　paths　of　CMO-SLM　is　little　more　than　that　of　G-SLM,　and　error　should　be　considered　when　a　pinhole　model　is　used　to　analysing　the　correlation.