For carrying out heavy ion single event effects (SEE) test, the tandem accelerator has the advantage of rapid replacement of ion species, making it possible to replace 5 or 6 kinds of ion in one experiment (about 20 h) and get complete cross-section curve for devices under test (DUTs). In order to achieve the purpose of rapid replacement of ion species, multi-element mixed target cone using in tandem accelerator has been developed. In this way variety of ions can be extracted in one target cone, the time of replacing target cone can be saved, thereby further raise efficiency of experiment. For carrying out heavy ion single event effects (SEE) test, the tandem accelerator has the advantage of rapid replacement of ion species, making it possible to replace 5 or 6 kinds of ion in one experiment (about 20 h) and get complete cross- section diagram for devices under test (DUTs). In order to achieve the purpose of rapid replacement of ion species, multi-element mixed target cone using in tandem accelerator has been developed. In this way variety of ions can be extracted in one target cone , the time of replacing target cone can be saved, thereby further raise efficiency of experiment.