Abstract: Stroke is the leading cause of disability and death. Transcranial stroke treatment has the advantages in noninvasiveness and low risk of intracranial hemorrhage. However, the parameters of transcranial focused ultrasound for the treatment of thrombotic ischemic stroke are still not clear at present. In this paper, a 3-D numerical simulation model is established based on head CT images of volunteers and an 82-element phase-controlled transducers array, and the time-domain finite difference method is used to analyze the Westervelt nonlinear acoustic propagation equation. The parameters such as ultrasonic excitation frequency and input sound power are selected by numerical simulation. The results show that when the frequency is the same, the greater the negative pressure formed at the focus, the greater the required input sound power, and the required input sound power for transcranial model is about 1.5 times that for craniotomy; And, the higher the frequency, the smaller the focal area, but the more the side lobes at the focal area. When the frequency is the same, the shape and size of the focal area for transcranial and craniotomy models are similar, but the side lobes for transcranial model are stronger. When the negative pressure formed at the focus reaches -6 MPa with thrombolytic effect and -8 MPa with significant thrombolytic effect, the required sound power first decreases and then increases with the increase of frequency, and the minimum appears at 0.8 MHz; Irradiation time and duty cycle have no effect on focal position and focal area.