In　recent　years,　it　was　found　that　magnetostrictive　ultrasonic　guided　wave　transducers　experimentally　excited　nonlinear　harmonic　components　under　a　certain　combination　of　dynamic　and　static　magnetic　fields.　However,　a　satisfactory　model　for　the　relevant　excitation　mechanisms　is　not　available.　In　this　study,　a　new　magnetostrictive　guided　wave　excitation　model　was　established　and　the　causes　for　harmonics　generation　were　analyzed.　In　addition,　the　calculation　results　of　the　model　were　obtained　under　different　magnetic　field　parameters.　We　firstly　changed　the　calculation　conditions　of　magnetostrictive　strain　in　the　model　and　then　theoretically　calculated　the　odd　and　even　harmonics　of　SH0　mode　ultrasonic　guided　waves　for　the　first　time.　Furthermore,　the　accuracy　of　the　model　was　experimentally　verified.　By　changing　the　strength　ratio　of　the　dynamic　magnetic　field　to　the　static　magnetic　field　(HD/HS),　the　excitation　amplitudes　of　odd　and　even　harmonics　could　be　regulated　with　a　magnetostrictive　sensor.　As　the　ratio　of　HD/HS　increased,　the　normalized　amplitude　of　the　second　harmonic　firstly　increased　and　then　decreased,　whereas　the　normalized　amplitude　of　the　third　harmonic　showed　an　exponential　growth　with　different　curvatures.　This　study　enriched　the　theory　of　magnetostrictive　guided　wave　excitation　and　provided　a　theoretical　basis　for　the　applications　of　magnetostrictive　sensors.