The invention discloses a method and an instrument for analyzing the energy indexes of the cerebral blood vessel. The method comprises the steps of: detecting out the blood flow velocity wave form, the numerical value, the blood vessel diameter and the pressure waveform of carotid artery; detecting out the diastolic pressure and the systolic pressure of a human body to obtain the pressure waveform and the numerical value of the carotid artery; then calculating out the total potential energy, the stable potential energy, the oscillation potential energy, the total kinetic energy, the stable kinetic energy, the oscillation kinetic energy, the total energy, the stable total energy and the oscillation total energy of the cerebral blood vessel, and finally calculating out the ration of the oscillation total energy to the total energy, the ratio of the total kinetic energy to the total energy, the ratio of the oscillation potential energy to the total potential energy and the ratio of the oscillation kinetic energy to the total kinetic energy of the cerebral blood vessel. The detection analysis instrument comprises a detection system, a control system and a computation analysis system, wherein the control system can send an operation command to each detection module and can also transmit the acquired data information to a master industrial personal computer. A series of indexes of the cerebral circulation blood flow energy can be comprehensively analyzed with an invasive method, therefore, the invention has great importance for the basic research and clinical application of the cerebral circulation.