Objective To study the relationship between the persistent nephrotic syndrome and damage of tubulointerstitium in children. Methods We observed the clinical and pathological features of children with the persistent nephrotic syndrome, who were divided into two groups according to their response to steroid: the refractory syndrome, and steroid sensitivity. Results ① Cases with damage of tubulointerstitium function had severe injuries of tubulointerstitium in pathology. ② There was a significant difference between the two groups in the level of urine β 2-MG, age, course of disease, and damage of tubulointerstitium in pathology. ③ Degrees of pathological damage of tubulointerstitium and pathological types had no significant difference. Conclusions The degree of tubulointerstitium pathological damage is an index of judgement on the therapeutic effect and prognosis of the persistent nephrotic syndrome.