AIM:To analyze principal causes of postoperative retinal re-detachment of simple rhegmatogenous retinal detachment(RRD) scleral buckling microsurgery in order to take effective measures and improve the success of surgery.METHODS:Fifteen cases(15 eyes) of postoperative retinal re-detachment of simple RRD Scleral Buckling microsurgery were studied to search for principal cause of retinal re-detachment.Then a conclusion was drawn that PVR was under B[1]in all retinal re-detachment cases.RESULTS:In post operative follow-up of 1 year,new split pore took place in 7 eyes(46.7%).Original split pore was not closed in 4 eyes(26.7%).Missing hole was in 2 eyes(13.3%).Detachment of choroid was in 1 eye(6.7%) and PVR was in 1 eye(6.7%).CONCIUSION:Principal causes of retinal re-detachment under Scleral Buckling microsurgery of RRD include new split pore,unenclosed original split pore and missing hole.