Efficiency　can　be　improved　through　the　cooperation　of　a　dual-robot　during　assembly.　However,　how　to　effectively　plan　a　simple　and　smooth　path　in　a　dynamic　environment　is　a　prominent　problem　in　the　process　of　dual-robot　cooperative　assembly.　In　this　paper,　a　method　based　on　RRT-Connect　algorithm　for　trajectory　planning　and　post-processing　for　trajectory　optimization　is　proposed.　This　method　takes　full　advantage　of　the　excellent　solution　ability　of　RRT-Connect　algorithm　in　the　complex　environment　so　as　to　obtain　the　initial　path　successfully.　Through　post-processing,　the　problem　of　RRT-Connect　non-convergence　to　target　is　optimized.　We　use　two　6-DOF　industrial　robots　to　build　an　experimental　platform　and　design　a　dual-robot　cooperative　assembly　system.　According　to　the　given　task,　the　system　can　generate　the　original　collision-free　path　based　on　RRT-Connect　algorithm.　Then　the　original　path　is　simplified　by　Floyd　algorithm　and　smoothed　by　multi-segment　Bezier　curve.　Finally,　the　time　parameter　is　sequenced　for　all　the　path　points　based　on　the　iterative　method,　and　the　effective　trajectory　is　obtained.　The　experimental　results　show　that　the　algorithm　proposed　in　this　paper　can　effectively　plan　and　optimize　the　trajectory　of　dual-robot.　Compared　to　other　methods,　this　approach　has　a　higher　success　rate　and　less　planning　time.