About　30nm　grain　sized　(K0.5Na0.5)　NbO3　powders　were　used　as　the　raw　materials,　and　the　solid　phase　method　was　used　to　prepare　potassium　sodium　niobate　ceramics　at　750~　950°C　under　normal　pressure　sintering.　The　abnormal　grain　growth　(AGG)　at　process　of　powder　sintering　was　investigated.　The　consequences　demonstrate　that　when　the　sintering　temperature　is　greater　than　850°C,　AGG　can　be　clearly　observed.　As　the　sintering　temperature　increases,　the　number　of　areas　where　abnormal　grain　growth　occurs　increases　as　well　as　the　size.　When　the　sintering　temperature　is　950°C,　the　area　of　abnormal　grain　growth　has　a　maximum　of　approximately　1mm　×　1mm,　and　it　has　good　(111)　orientation.　The　difference　in　the　sintering　driving　force　caused　by　the　size　distribution　in　the　potassium　sodium　niobate　nano　powder　is　the　root　cause　of　abnormal　grain　growth.　©　Published　under　licence　by　IOP　Publishing　Ltd.