Rare-earth　orthoferrites　(RFeO3)　have　received　significant　attention　due　to　their　intricate　magnetic　interactions　and　potential　applications　in　ultrafast　spintronic　devices.　Among　them,　DyFeO3　exhibits　rich　magnetic　phase　transitions　driven　by　the　interplay　between　Fe3+　and　Dy3+　sublattices.　Previous　studies　mainly　focused　on　temperature-induced　spin　reorientation　near　the　Morin　temperature　(T-M　similar　to　50　K),　but　there　has　been　limited　exploration　of　magnetic　phase　behavior　under　external　fields　above　T-M.　This　work　aims　to　systematically　investigate　the　temperature-　and　magnetic-field-dependent　magneto-dynamic　properties　of　a-cut　DyFeO3　single　crystals,　with　an　emphasis　on　identifying　novel　phase　transitions　and　elucidating　the　underlying　mechanisms　involving　Fe3+-Dy3+　anisotropic　exchange　interactions.　High-quality　a-cut　DyFeO3　single　crystals　are　grown　using　the　optical　floating　zone　method　and　characterized　by　X-ray　diffraction　(XRD)　and　Laue　diffraction.　Time-domain　terahertz　spectroscopy　(THz-TDS)　coupled　with　a　superconducting　magnet　(0-7　T,　1.6-300　K)　is　employed　to　probe　the　ferromagnetic　resonance　(FM)　and　antiferromagnetic　resonance　(AFMR)　modes.　By　analyzing　the　frequency　trends　in　the　spectra,　the　response　of　internal　magnetic　moments　to　external　stimuli　can　be　inferred.　In　the　zero　magnetic　field　experiment,　it　is　found　that　the　temperature　induced　spin　reorientation　(Gamma(4)-＞Gamma(1))　occurs　at　Morin　temperature　(similar　to　50　K)　with　temperature　decreasing.　A　broadband　electromagnetic　absorption　(0.45-0.9　THz)　occurs　below　4　K,　which　is　attributed　to　electromagnons　activated　by　broken　inversion　symmetry　in　the　Dy3+　antiferromagnetic　state.　Above　the　Morin　temperature,　the　absorption　spectra　of　the　sample　are　measured　at　constant　temperatures　(70,　77,　90,　100　K)　and　magnetic　fields　ranging　from　0　to　7　T.　The　experimental　results　show　that　with　the　increase　of　magnetic　field,　a　new　magnetic　phase　transition　occurs　(Gamma(4)　-＞　Gamma(24)　-＞　Gamma(2)　-＞　Gamma(24)　-＞　Gamma(2)),　and　the　critical　magnetic　field　of　the　phase　transition　varies　with　temperature.　The　phase　transitions　arise　from　the　competition　between　external　magnetic　fields　and　internal　effective　fields　generated　by　anisotropic　Fe3+-Dy3+　exchange.　These　findings　contribute　to　the　further　understanding　of　the　magnetoelectric　effects　in　RFeO3　systems　and　provide　a　roadmap　for　using　field-tunable　phase　transitions　to　design　spin-based　devices.