The　essence　of　the　multidisciplinary　collaborative　design　problem　(MCDP)　is　the　coordination　of　the　design　variables　among　multiple　disciplines　on　the　basis　of　the　all　constraints　of　all　disciplines.　There　exist　some　problems　such　as　the　early　detection　of　design　conflicts　and　the　determination　of　the　consistency　domains　of　the　design　variables,　etc.　The　resolving　of　these　problems　can　help　designers　avoid　bad　decision-making,　reduce　the　design　iteration　and　improve　the　design　efficiency.　Aiming　at　the　problems,　this　paper　proposes　a　constraint-net　model　to　describe　and　manage　all　the　design　variables　and　constrains　of　all　disciplines,　discusses　the　reformulating　method　of　the　MCDP　to　improve　computation　efficiency,　and　develops　the　interval　propagation　algorithm　to　determine　the　consistency　domains　of　the　design　variables,　etc.　A　gear　drive　is　taken　as　an　example　to　illustrate　the　effectiveness　of　the　proposed　method.