An　error　distribution　space　method　to　describe　the　operation　precision　caused　by　flexible　joint　errors　was　proposed.The　operating　errors　of　each　joint　were　coupled　to　obtain　the　possible　regions　of　the　real　operating　points　in　space,　and　the　operating　accuracy　of　the　robot　along　all　directions　was　obtained.The　algorithm　for　error　distribution　space　was　given,　and　the　problem　of　exponential　multiplication　with　dimension　was　solved　by　increasing　dimension　of　low-dimensional　error　space.The　error　distribution　characteristics　in　the　process　of　closed-chain　coordinated　operation　was　studied,　and　the　influence　of　the　self-motion　characteristics　of　redundant　robot　joints　on　the　precision　of　closed-chain　coordinated　operation　was　analyzed　based　on　the　error　distribution　space　method.Research　result　shows　that　the　joint　configuration　corresponding　to　the　same　operating　precision　is　not　unique　and　the　joint　angle　corresponding　to　the　minimum　error　in　the　operating　space　is　not　continuous.Therefore,　a　method　of　trajectory　planning　with　minimum　error　based　on　the　least　square　method　was　proposed,　and　its　validity　was　verified　by　simulation.　©　2019,　Editorial　Board　of　Journal　of　Huazhong　University　of　Science　and　Technology.　All　right　reserved.