A light-emitting device, comprising: a light source , configured to emit excitation light (λ21, λ41, λ51); a beam-splitting-combining plate disposed in an outgoing light path of the excitation light (λ21, λ41, λ51), wherein the beam-split-combination plate includes a beam-splitting portion configured to split the excitation light (λ21, λ41, λ51) into a first excitation light (λ211, λ411, λ511) and a second excitation light (λ212, λ412, λ512) along different propagation paths; a first wavelength conversion device disposed in an outgoing light path of the first excitation light (λ211, λ411, λ511), and including a first wavelength converting layer configured to absorb the first excitation light (λ211, λ411, λ511) to generate first excited light (λ22, λ42, λ53), and reflect the first excited light (λ22, λ42, λ53) back to the beam-splitting-combining plate ; and a second wavelength conversion device disposed in an outgoing light path of the second excitation light (λ212, λ412, λ512) and configured to reflect the second excitation light (λ212, λ412, λ512) back to the beam-splitting-combining plate , wherein the beam-splitting-combining plate further includes a beam-combining portion disposed around the beam-splitting portion , and the beam-combining portion is configured to combine the first excited light (λ22, λ42, λ53) and the second excitation light (λ212, λ412, λ512) respectively reflected to the beam-splitting-combining plate into one beam, wherein the beam-splitting portion is disposed at a central area of the beam-splitting-combining plate , and characterized in that the beam-splitting portion includes a semi-transmitting and semi-reflecting film for light in a particular wavelength range. a light source , configured to emit excitation light (λ21, λ41, λ51); a beam-splitting-combining plate disposed in an outgoing light path of the excitation light (λ21, λ41, λ51), wherein the beam-split-combination plate includes a beam-splitting portion configured to split the excitation light (λ21, λ41, λ51) into a first excitation light (λ211, λ411, λ511) and a second excitation light (λ212, λ412, λ512) along different propagation paths; a first wavelength conversion device disposed in an outgoing light path of the first excitation light (λ211, λ411, λ511), and including a first wavelength converting layer configured to absorb the first excitation light (λ211, λ411, λ511) to generate first excited light (λ22, λ42, λ53), and reflect the first excited light (λ22, λ42, λ53) back to the beam-splitting-combining plate ; and a second wavelength conversion device disposed in an outgoing light path of the second excitation light (λ212, λ412, λ512) and configured to reflect the second excitation light (λ212, λ412, λ512) back to the beam-splitting-combining plate , wherein the beam-splitting-combining plate further includes a beam-combining portion disposed around the beam-splitting portion , and the beam-combining portion is configured to combine the first excited light (λ22, λ42, λ53) and the second excitation light (λ212, λ412, λ512) respectively reflected to the beam-splitting-combining plate into one beam, wherein the beam-splitting portion is disposed at a central area of the beam-splitting-combining plate , and characterized in that the beam-splitting portion includes a semi-transmitting and semi-reflecting film for light in a particular wavelength range. <EOS>