The utility model provides a lamp tube for a shade lamp, which relates to the field of lighting. The lamp tube comprises a tube body and a core column, wherein a filament and an exhaust pipe are arranged on the core column; and amalgam is filled in the exhaust pipe. A part of the exhaust pipe is squashed, and the amalgam is positioned in the squashed part of the exhaust pipe, so that the consistency of the working temperature of the amalgam is ensured, the position change of the amalgam caused by melting and flowing when being ignited for a long time is avoided, the amalgam can be kept in an optimum operating temperature, the optimal saturation vapor pressure of the mercuric can be achieved, and the consistency of the photoelectric parametric is greatly improved, which is of great benefit to the improvement of lumen maintenance of the whole lamp, and the prolonging of the service life of the lamp.