There are differences between blood test for renal function and renal ultrasound in terms of examination methods, examination contents and reflecting diseases. 1. Inspection method: blood test for renal function is mainly to draw blood through vein, and use all kinds of testing equipment to analyze the blood so as to achieve the purpose of inspection, renal ultrasound is to use ultrasound equipment to observe the parts to be inspected through ultrasound probe, both of them belong to the auxiliary inspection, but in a different way. 2. Examination content: blood test of renal function is mainly to examine creatinine, urea, uric acid, carbon dioxide binding capacity and other related indexes, through the above examination can assess the renal function; renal ultrasound is to examine the size and location of the kidney, whether there is hyperplasia, tumor, stones, fluid, renal parenchyma thickness and so on. 3. Reflecting diseases: renal function test can suggest the existence of renal insufficiency, hyperuricemia, metabolic acidosis and so on; renal ultrasound mainly reflects that the patient may suffer from kidney stones, renal cysts, renal tumors, chronic kidney disease and other diseases. Clinically, in order to assess the kidney function, it is generally necessary to improve the above two examinations to comprehensively assess the condition. Both of the above methods are for kidney examination, but the appropriate method should be chosen under the guidance of doctors according to the situation.