Objective To explore the effect factors on the related measurement guidelines of renal area and renal cortex thickness by measurement of CT/MRI radiography in vivo kidney in adults. Methods Thickness of renal cortex (TC), cortical area (CA), parenchymal area (PA), as well as cortical faction (CF, cortical/parenchymal area) of 164 cases (106 cases with enhanced CT abdomen and 58 cases with MRI abdomen scanning) without renal disease was calculated bilaterally. All data were analyzed by SPSS 11.5 (the mean of two groups and multi-groups was compared by t test and analysis of variance, respectively).Results ① In CT scan, the mean value and 95% confidence interval of TC，CA，PA and CF were 0.62 (0.44 to 0.80) cm, 7.2 (4.1 to 10.2) cm2, 18.2 (10.7 to 25.7) cm2, 39.3 (30.3 to 48.3) % on the left, and 0.63 (0.43 to 0.83) cm, 7.3 (4 to 11) cm2, 18.1 (11 to 25.3) cm2, 39.9 (32 to 48) % on the right, respectively. Likewise, in MRI, those were 0.58 (0.33 to 0.83) cm, 7.5 (3.5 to 11.3) cm2, 14.8 (8.5 to 21.1) cm2, 50.2 (32.8 to 67.6) % on the left, and 0.55 (0.31 to 0.79) cm, 7.3 (4.4 to 10.3) cm2, 15.6 (10.1 to 21.1) cm2, 47.3 (30 to 65) % on the right. ② There was a significant difference in the value of TC, CA, PA between different gender and age groups, and were decreased with the age increaseing. ③ Most of the values measured by MRI were less than those by CT. Conclusions The study suggests that the values of TC, CA, PA and CF can well represent the renal size and function, and may offer a practical and significant normal standard in the radiological diagnosis.