<p>NiMnGa Ferromagnetic shape memory alloy (FSMA) is considered highly promising for applications in actuators and sensors. However, the comprehensive mechanism of NiMnGa FSMA during cyclic deformation remains unclear. In this paper, a magneto-mechanically coupled phase-field finite element model for NiMnGa FSMA is developed, which separately considers the energy barrier and potential energy of martensite variants when considering the Landau-type double-well potential energy. The cyclic deformation induced by magnetic-mechanical dual fields is simulated, and the results are consistent with experimental observations. Besides, the phase-field finite element simulations successfully capture the evolution of microstructural morphology, revealing the deformation and magnetization mechanisms induced by magnetic-mechanical dual fields and their dependence on the loading level.</p>