The so-called increased blood flow in the left middle cerebral artery is actually the result of transcranial Doppler ultrasonography, or TCD terminology. There are two general causes of increased blood flow in the left middle cerebral artery, as follows: 1, caused by cerebral vasospasm, patients may have vasospastic conditions due to, for example, poor sleep, anxiety, and tension. When doing Doppler examination, it shows that the middle cerebral artery blood flow is faster; 2, caused by vascular stenosis, the lumen will become smaller and thinner after vascular stenosis, resulting in faster blood flow through the speed, in this case, it is recommended that patients do head CTA or nuclear magnetic angiography to clarify whether there is the actual situation of vascular stenosis. If cerebral vasospasm is considered, oral vascular antispasmodics, such as nimodipine and flunarizine hydrochloride, can be administered symptomatically to relieve the vasospasm. If it is caused by vascular stenosis, especially severe stenosis, interventional treatment may be required. Of course, risk factors should be clearly identified to slow down the progression of the disease by targeted control.