Abstract: Objective To observe the morphological and functional characteristics of the left atrium in people with different blood pressure grades, and analyze the impact of blood pressure on left atrium function. Methods A total of 382 patients who were first diagnosed with abnormal blood pressure in the cardiology department of Chengdu First People’s Hospital from January 1, 2019 to March 31, 2022 were selected, 57 patients were enrolled in the normal blood pressure group, 118 in the high-normal value of blood pressure group, 109 in the mild hypertension group（grade one hypertension level） and 98 in the moderate to severe hypertension group（grade two or three hypertension level）. The general data and routine ultrasound data of the population were collected. Real-time three-dimensional echocardiography（RT-3DE） and Two-dimensional spot tracking technology（2D-STE） were used to obtain relevant parameters of the left atrium, including left atrial volume index（LAVI）, left atrial peak positive strain rater（LASRs）, left atrial peak early negative strain rate（LASRe）, left atrial peak late negative strain rate（LASRa）, left atrial filling fraction（AFF）, left atrial active ejection fraction（LAAEF）, left atrial passive ejection fraction（LAPEF）, left atrial mechanical dispersion（MD）. The morphological and functional characteristics of the left atrium were evaluated, and then comparative analysis among different groups was conducted. A linear regression analysis was developed to assess the effect of blood pressure level on left atrial function after excluding confounding factors of age, gender, and body surface area（BSA）. Results From the normal blood pressure group to the moderate to severe hypertension group, the left atrial channel function and reserve function decreased gradually LASRe:（2.9±0.7） vs（2.4±0.7） vs（2.0±0.5） vs（1.7±0.6） s^-1, F=55.095, P＜0.001; LASRs:（4.5±0.9） vs（4.1±0.8） vs（3.6±0.7） vs（3.2±0.8） s^-1, F=39.762, P＜0.001. The pump function increased gradually from the high-normal value of blood pressure group to the mild hypertension group. In the moderate to severe hypertension group, booster pump function reduced. The difference of MD among the four groups was statistically significant. After adjusting for age, sex and BSA, linear regression analysis showed that LAAEF, AFF, LASRe and LASRs changed during the period of high-normal value of blood pressure（P＜0.05）. Conclusions Left atrial function is sensitive to the change of blood pressure, and there is functional change in the high-normal value of blood pressure stage.