Background: Although there are many biochemical indicators to reflect changes in renal function, but these indicators can not reflect renal damage timely and accurately. Renal microcirculation changes can not be reflected also. This study amied at evaluate significance of renal perfusion angiography and the indexes of relevant biochemical in early diagnosis of type 2 diabetic nephropathy. Methods: 30 I-III T2DN patients (DN group) and 25 healthy volunteers (control group) were studied, and both of groups were performed renal perfusion CT angiography imaging examination. Biochemical indexes, which are fasting blood glucose (FBG), urinary albumin excretion rate (UAE), 24 h urine protein quantitation (UPQ), blood urea nitrogen (BUN), serum creatinine (Scr), Cystatin C(Cys C), random albumin to creatinine ratio(ACR), were measured in both of groups, then simplified MDRD (Modification of Diet in Renal Disease) and Cys C equation were used to calculate the Estimated Glomerular Filtration Rate(eGFR). double-renal perfusion contrast scanning in both of groups were also conducted to obtain data of double renal blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface (PS) for statistical analysis. Results: The indexes of BF, MTT and FBG, UAE, 24 h UPQ, ACR, Cys C, eGFR were found to have relative strong correlation and statistical significance (P<0.05). BF was shown the negative correlation with those indexes, however MTT had positive correlation with them. The area under ROC (receiver operating characteristic curve), were more than 0.9 for UAE, ACR, NF, and MTT, and it indicate that these indexes have relatively positive effect on the early diagnosis of the DN. For 24 h UPQ, cysteine C, eGFR and BV value, the area Under the curve are between 0.7 and 0.9, which indicates that diagnosis using those index for the disease were accuracy. Thus, the above indexes have better diagnostic efficiency compared to Scr, BUN and eGFR. Conclusion: The biochemical indexes such as UAE, ACR and renal perfusion indexes such as BF and MTT can be applied in the early predicative diagnosis and DN screening. Its diagnosis effect is better than other biochemical indexes.