Objective To study the changes of serum free triiodothyronine (FT3), free tetraiodothyronine (FT4) and the relation between free thyroxine levels and serum tumor necrosis factor (TNK), albumin (ALB), urinary protein in children with primary nephrotic syndrome(PNS). Methods There were sixty children who were suffered from nephrotic syndrome in study group Serum FT3,FT4,TNF, Alb and urinary protein were detected. In the meantime compared with 25 health,cases. Results The levels of FT3, FT4 of the children who were suffered from nephrotic syndrome were lower. The difference between nephrotic syndrome and health cases were significantly (P