A novel testing machine for a continuous semisolid extending extrusion process (CSEP) has been designed and used to produce AA2017 alloy flat bar. Fine and homogeneous grains of AA2017 slurries with rosette structures were obtained at suitable casting temperatures. During preparation of semisolid AA2017 alloy by the proposed process, rosette grain formation was observed during the application of the large force provided by the rough roll. By controlling casting temperature, AA2017 products were produced with fine surfaces and rectangular transections of 14×25 mm. A casting temperature range of 710–750℃ was suggested. The microstructure of the product is fine and even with striped appearance and is composed mainly of h and a phases. The fracture strength of AA2017 product produced by the semisolid extending extrusion process is improved by 100 MPa, and elongation by 29%.