It　is　well　acknowledged　that　high　nitrate　concentration　would　negatively　affect　the　biological　denitrification　activity,　especially　in　the　presence　of　nitrite　accumulation.　In　this　study,　a　novel　granular　partial　denitrification　(PD)　process　was　developed,　and　the　impact　of　nitrate　concentration　(120-960　mg　N/L)　on　PD　granules　was　investigated　by　close　monitoring　of　the　operational　performance,　physicochemical　characteristics,　and　microbial　community.　Results　indicated　that　the　effluent　nitrite　increased　with　the　nitrate　concentration,　with　a　maximum　value　of　492.4　mg　N/L　obtained.　And　the　maximum　denitrification　activity　in　situ　was　found　not　to　be　decreased　despite　high　nitrite　accumulation;　it　was　maintained　at　0.24　g　N/g　VSS/h,　suggesting　the　high　tolerance　of　PD　granules　to　the　nitrite.　The　granule　size　increased　with　the　influent　nitrate,　and　the　compact　PD　granules,　however,　were　observed　to　be　disintegrated　at　960　mg　N/L　of　nitrate,　which　was　likely　attributed　to　the　substrate　diffusion　limitation　in　larger　granules,　with　the　cavity　formed　in　its　inner　part.　In　addition,　microbial　analysis　revealed　that　bacterial　richness　and　the　diversity　of　PD　granules　were　decreased,　and　Gracilibacteria　that　was　supposed　to　be　responsible　for　maintaining　the　PD　granule　structure　was　largely　reduced　at　a　high　nitrate　concentration,　which　was　likely　to　be　another　major　reason　for　the　disintegration.　This　study　revealed　the　potential　causes　for　the　disintegration　of　PD　granules,　which　offer　theoretical　support　and　technical　guidance　to　ensure　the　stability　of　PD　granules　in　treating　high　nitrate　wastes　for　efficient　nitrite　production.