The invention discloses the technical field of reconstruction of existing highway bridges, and particularly relates to a beam end expansion device of an embedded track and a construction method. According to the beam end expansion device of an embedded track and the construction method a first member and a second member are arranged in a matched mode; the first member includes an opening, the first member is arranged on the top surface of a right side beam end structure; one end of the second member is arranged on the top surface of a left side beam end structure, the other end of the second member is arranged in the opening, an elastic body is arranged between the left side beam end structure and the right side beam end structure, and a waterproof material is further arranged between theelastic body and the second member. During work, the distance between the groove bottom surface of the opening and the second member is, namely, the maximum allowable expansion amount of the beam end;the beam end expansion and contraction of the embedded track can be achieved by elastic deformation of the elastic body and the cooperation of the second member and the first member; and the problemthat a traditional track structure inevitably conflicts with expansion joints of an original highway is solved, continuity of bridge floors in a track area can be maintained and waterproofness and durability of track areas at the beam end can be met meanwhile.