Children with persistent cough usually need to do imaging tests, blood tests, C-reactive protein, mycoplasma antibodies and other tests. 1. Imaging tests: If the cough is not relieved, imaging tests, such as chest X-ray, chest CT, etc., can be done to check whether the child has bronchitis or pneumonia and other diseases. 2. routine blood test: pediatric cough has been bad can check routine blood test, check the blood white blood cells, neutrophils, eosinophils, monocytes, red blood cells, platelets, hemoglobin and other items are normal. 3. C-reactive protein: C-reactive protein test is important for differential diagnosis of bacterial and viral infections. Therefore, if the child has been coughing badly, you can check whether the C-reactive protein is normal, which is of great significance to the clinical use of drugs. 4. Mycoplasma antibody: If the child’s cough does not subside and the routine blood test is normal, you can check whether there is mycoplasma infection through mycoplasma antibody. When a child’s cough is not good, it is necessary to go to the hospital in time to check the specific cause and treatment, so as not to delay the condition.