Objective To explore the glomerular change of renin-angiotensin system (RAS) expression in ATIaR gene knockout mice and its effects on extracellular matrix (ECM) remodeling under diabetic condition. Methods ATlaR knockout mice were generated previously. Hyperglycemia was induced by peritoneal injection of streptozotocin in ATIaR knockout mice and wild type mice. Normal AT1aR knockout mice and wild type mice were used as control group. Twelve weeks later, kidneys were harvested and frozen quickly in dry ice-acetone. Glomendi were collected by laser capture microdissection and total RNA was extracted, mRNA expression of AT1aR, AT1bR, AT2R, angiotensinogen, ACE, renin, and CYP11B2 was assessed by real-time PCR. ECM accumulation was evaluated by PAS staining. Protein levels of transforming growth factor β1(TGF-β1), type 1 plasminogen activator inhibitor(PAI-1), monocyte chemotactie protein 1(MCP-1) and renin were semi-quantitated by immunostaining. Results Compared to the wild type, mRNA expression of AT1bR, angiotensinogen, renin, CYP11B2 within glomeruli was upregulated significantly in ATlaR knockout mice (P<0.05), but no change of ACE expression was found in these two groups. AT2R protein was poorly detected in AT1aR knockout glomeruli and downregulated in wild type glomemli. ECM accumulation was significanfly increased associated with the parallel increase in TGF-β1, PAI-1, MCP-1 and renin within glomendi (P <0.05). Conclusions AT1aR gene knockout cannot improve ECM deposition in diabetic nephropathy. The compensate change of RAS components may be involved in this scenario: upregulation of AT1bR, downregulation of AT2R. CYP11B2 and renin may function in a novel pathway.