Renal fibrosis, especially tubulointerstitial fibrosis, is the most common pathway of all chronic kidney diseases progressing to end-stage renal diseases. Several adaptive reactions occur in renal tubular epithelial cells after chronic injury, such as changes in glycolipid metabolism, unfolded protein response, autophagy and senescence, epithelial-to-mesenchymal transition and G2/M cell cycle arrest. Maladaptive repair mechanisms can induce tubulointerstitial fibrosis. This article will discuss the molecular mechanism of these adaptive responses of renal tubular epithelial cells driving renal tubulointerstitial fibrosis, and provide a basis for exploring new drug targets for renal tubulointerstitial fibrosis.