In　this　study,　we　utilized　time-domain　terahertz　magneto-optical　spectroscopy　to　investigate　the　spin　resonance　in　a　c-cut　TmFeO3　single　crystal　at　T　=　1.6　K　under　different　magnetic　fields　and　characterized　its　intricate　internal　interactions.　By　selectively　exciting　the　magnetic　resonance　modes　in　the　crystal,　we　found　that　as　the　magnetic　field　increases,　the　quasi-ferromagnetic　(q-FM)　mode　of　TmFeO3　single　crystal　shifts　towards　higher　frequencies,　while　the　quasi-antiferromagnetic　(q-AFM)　mode　transforms　into　the　q-FM　mode　at　low　critical　magnetic　fields　(2.2-3.6　T).　Through　magnetic　structure　analysis　and　theoretical　calculations,　it　is　confirmed　that　the　magnetic　moment　of　TmFeO3　undergoes　a　magnetic-field-induced　spin　reorientation　from　Gamma　2　to　Gamma　4　phase.　Materials　with　magnetic　moment　flipping　at　low　magnetic　fields　may　find　applications　for　antiferromagnetic　spintronic　devices　in　the　future.