Objective To investigate the characteristic and the value of renal solid lesions' boundary at contrast-enhanced ultrasonography(CEUS). Methods The study included 225 patients (124 males, 101 females) with renal 239 solid lesions [133 renal cell carcinoma(RCC) and 106 benign lesions]. The enhanced mode of lesion boundary at CEUS was observed. The histopathologic pseudocapsule of RCCs was analysed.Results Enhanced modes of all lesions' boundary at CEUS were classified as: type Ⅰ , iso-enhanced boundry in whole phase, 82.85 % (198 of 239) ;type Ⅱ , a perilesional annular highly-enhanced signal at early phase,4.18% (10 of 239);type Ⅲ ,perilesional annular highly-enhanced signal in whole phase,9.62% (23 of 239) ;type Ⅳ, perilesional annular highly-enhanced signal in midium and late phase, 1.25 % (3 of 239) ;type Ⅴ ,iso-enhanced boundry in the mdium and late phase with no enhancment at early phase, 2. 09% (5 of 239). The distribution of types Ⅰ , Ⅱ , Ⅲ between groups were significant different( P=0.000, 0.046,0. 000), the type Ⅳ and Ⅴ was not ( P = 0.256,0.068). The distribution of perilesional annular highlyenhanced signal between benign and RCC groups was statistically different (x2=29. 681, P=0.000).Regared it as a diagnostic criteria of RCC,the sensitivity was 26.32% (35/133) ,the specificity was 99.06%(105/106) ,the positive predictive value was 97.22% (35/36),the negative predictive value was 51.72%(105/203) ,and the accuracy was 58.58% (140/239). The perilesional annular highly-enhanced signal was not correlated with the pseudocapsule in pathology ( P = 1. 000). Conclusions The boundary enhancement mode of renal solid lesions at CEUS was divided into five types. The perilesional annular highly-enhanced signal was important in diagnosis of RCC,which was not correlated with the pseudocapsule in pathology.