Abstract: Objective To investigate the effects of uric acid on left ventricular hypertrophy and diastolic function in young hypertensive patients with different body mass indexes（BMI）. Methods A total of 237 young patients with hypertension diagnosed at the Lanzhou University Second Hospital from January 2018 to September 2019 were enrolled.According to BMI,they were divided into 3 groups:normal group（BMI 18.5-＜24;n=82）,overweight group（BMI 24-＜28;n=90）and obesity group（BMI≥28 kg/m~2;n=65）. According to the tertiles of uric acid level,patients were divided into low tertile group（uric acid＜330.00;n=78）,middle tertile group（uric acid330.00-＜412.67;n=80）and high tertile group（uric acid≥412.67μmol/L;n=79）.The general information,biochemical indicators（including uric acid）and echocardiographic parameters were collected and analysed. Results（1）A tendency towards higher uric acid（339.82±96.78）vs（384.27±98.50）vs（415.02±105.59）μmol/Lwas seen with the increase of BMI（all P＜0.05）. Some echocardiography parameters,such as left ventricular end-diastolic diameter（LVEDd）（45.01±5.18）vs（45.82±4.40）vs（48.66±5.16）mmand E/e’9.73（7.79-12.13）vs 9.94（8.66-11.64）vs 11.00（9.28-13.48）worsened if subjects were more obese,the obesity group was significantly higher than the normal group and the overweight group（all P＜0.05）,but the difference between the normal group and the overweight group was not statistically significant（P＞0.05）.With the increase of BMI,thickness of the posterior wall of the left ventricle at the end of diastole（LVPWTd）8.50（7.50-9.43）vs 8.80（8.00-9.63）vs 9.60（8.75-10.85）mmincreased successively,and the difference between the normal group and the obese group was significant（P＜0.05）.（2）With the increase of uric acid level,the BMI24.00（22.38-26.00）vs 24.91（22.90-28.38）vs 27.10（24.70-29.94）kg/m~2and E/e’9.90（8.36-11.63）vs 10.29（8.67-12.13）vs 10.60（9.00-13.06）of the three groups of patients in the low tertile group,middle tertile group and high tertile group increased successively,and the differences between every two groups were statistically significant（all P＜0.05）.（3）Variance analysis of two factors showed that high uric acid level and obesity have an interactive effect on E/e’（F=1.819,P=0.026）,and the combination of them will further aggravate LVH and impair left ventricular diastolic function.（4）Partial correlation analysis showed that uric acid was positively correlated with LVMI and E/e’in the obesity group（r=0.267,P=0.032）and E/e’（r=0.339,P=0.010）;but the correlation was not observed in the other two groups.（5）Multivariate stepwise regression analysis using LVMI and E/e’as dependent variables respectively showed that LVMI was positively correlated with systrolic blood pressure and uric acid;E/e’was positively correlated with BMI and diastolic blood pressure and negatively correlated with gender（assume 1 for men and 2 for women）. Conclusions Among young hypertensive patients,obese individuals have higher uric acid levels,higher LVMI and worse left ventricular diastolic function. The effects of uric acid and obesity on hypertension-mediated cardiac organ damage are superimposed and interactive. Uric acid plays an important role in the development of obesity-related LVH and left ventricular diastolic dysfunction in young hypertensive patients.