In order to solve the problems of low detection efficiency of the dynamic aperture emission and nonuniform resolution of the dynamic depth of focusing (DDF) in different depths, a multidepth focusing phased array emitting scheme is designed by combining the advantages of the two technologies in this paper. After analyzing the relationship between the spatial resolution of the ultrasonic phased array imaging and the parameters of linear array structure, an emission method of symmetrically partial emitting is confirmed eventually. After demarcating focalwidth as 7 mm and focaldepth as 50 mm, the detecting range higher limit is confirmed as 110 mm. By contrasting with the imaging simulations of different emission methods, the proposed emission method is proved to be effective in improving the resolution nonuniformity and detecting dynamic range attenuation.