The present invention provides method and device for trackball-based press positioning, so as to effect a press-positioning operation on a trackball. According to the method, when the trackball is under pressure, the multi-legged support that supports the trackball will be deformed, and then transmits the deformation information to the processing module. The processing module compares the deformation information with the deformation threshold information stored therein. When it is determined that the trackball is under pressure but not in contact with the pressure sensing module, the trajectory of the trackball is recorded by the positioning module, and corresponding operations are performed on the displayed information in accordance with the trajectory. The press positioning information of the trackball may be recognized according to the present invention, and corresponding operations may be determined in accordance with the information. As a result, the accuracy of the recognition result at the mobile terminal and the accuracy of the final operation on information displayed on a screen will be increased.