It may be normal for blood pressure to be different between lying down and sitting, but if the pressure difference is too great, it may also be due to vascular disease. When lying down, blood flows back to the heart, so the heart pumps significantly more blood each time, a situation that can lead to greater pressure on the sidewalls of the blood vessel walls. While sitting, part of the blood will be gathered to the lower limbs, resulting in a decrease in the amount of bleeding from the heart, and the pressure on the side walls of the blood vessel walls is slightly smaller, so the measured blood pressure will be different. In general, the difference between sitting and lying blood pressure is not more than 20mmHg, if the difference is too large, there may be vascular lesions, such as atherosclerosis, vascular stenosis, etc., need to go to the hospital in time for further examination. When lying and sitting blood pressure is not the same, after excluding physiological factors, it is recommended to go to the hospital as soon as possible to find out the cause of the disease, and then follow the doctor’s instructions for treatment.