Time-varying　loads,　manufacturing　errors,　and　assembly　errors　are　the　main　factors　leading　to　the　performance　degradation　of　the　planetary　roller　screw　mechanism.　This　paper　proposes　a　comprehensive　analysis　method　for　the　performance　degradation　of　the　planetary　roller　screw　mechanism　caused　by　time-varying　loads　and　manufacturing　and　assembly　errors.　Firstly,　a　simulation　analysis　model　of　the　planetary　roller　screw　mechanism　was　established　and　its　effectiveness　was　verified.　A　quantitative　analysis　was　conducted　on　the　influence　of　manufacturing　and　assembly　errors　on　the　load　distribution,　revealing　the　load-bearing　mechanism　under　the　influence　of　errors.　Secondly,　loading　experiments　were　conducted　on　the　planetary　roller　screw　mechanism,　and　the　degradation　of　its　load-bearing　performance　was　divided　into　the　normal　degradation　stage,　the　accelerated　degradation　stage,　and　the　failure　stage.　The　experimental　results　prove　that　the　initial　transmission　accuracy　has　a　significant　impact　on　the　degradation　of　the　load-bearing　performance,　determining　the　occurrence　of　the　node　where　the　accelerated　degradation　stage　appears　in　the　load-bearing　performance.　Thirdly,　the　wear　status　of　the　threads　and　gears　was　examined,　and　the　results　showed　that　material　peeling　was　the　main　factor　causing　the　degradation　of　load-bearing　performance.