Objective:Currently

the focal region size of spherical transducers used in the focused ultrasound surgery is very small

when use this kind of transducer treat large tumors need a long time to complete the treatment.In order to solve this problem

this paper present a new way to form a larger treatment thermal field through combinate multi-focus.Methods:Using MATLAB 7.0 computing software that comes with the genetic algorithm toolbox ’gads’ pairs of phased array ultrasonic transducer optimization of multi-focus mode.In the three focus

five focus mode to change the focus of the distance between the focus and make it a major focal region sound field mode.Results:In the shorter the distance between the focus

the isolated focus of the sound field into a three-line continuous sound field;5 focus on the sound field into a butterfly-shaped sound field

and ultimately tends to form a circular focal region.Conclusion:The change in spacing between the focal point of the number and size of the focus

you can effectively focus on preparation of large multi-focal region sound field model for the realization of HIFU to treat large areas quickly and effectively laid the foundation for lesions.