[Objective]To explore the effects on surrounding tissue and bone regeneration by citrated calcium sulphate(CCaS) and Ostesset~.[Method]Bilateral or lateral femoral condyles were drilled into defects in 18 rabbits,and divided into 3 groups: A,12 rabbits,left defect filled with CCaS cylinder,right defect with osteoset~;B,3 rabbits,left defect with CCaS,right defect blank;C,3 rabbits,left defect with osteoset~GFDA3,right defect blank.The rabbits were sacrificed at 3 wks,6 wks and 13 wks,and defect samples were taken for histological exam,roengenographic observation and bone tissue calculation by image-plus CCD system.[Result]The defects that were not grafted were filled with bone marrow and there was minimal new bone,only at the margen of the defects CCaS and osteoset~GFDA3 implanted in the defects were gradually absorbed,and substituted by new bone trabecula,which became more mature and thicker.The area fraction and trabecula thickness of new bone in defects treated with CCaS were not significantly different from defects treated with osteoset~ after 3,6,13 wks.However,the degradation velocity of CCaS was slower than that of osteoset~.No inflammatory and foreign body response was observed.[Conclusion]Just like osteoset~,CCaS is more benefitial to new bone formation compared with osteoset~,because CCaS has relatively slower degradation velocity.