Disclosed is an assembly for aligning a rotating shaft of a rotating table type laser direct writing device to the direct writing optical axis. The direct writing device comprises a laser source, a laser path and a rotating table, wherein a laser modulator, a first reflector, a second reflector and a microscope objective are sequentially arranged on the laser path, laser beams are modulated by the laser modulator and then reflected by the first and second reflectors to be incident onto the microscope objective, and the tabletop of the rotating table is perpendicular to the direct writing optical axis. The alignment assembly comprises a panel piece and a digital imaging system, wherein a metal film is arranged on one side of the panel piece, the panel piece is fixed to the tabletop of the rotating table, the metal film faces the microscope objective, and the digital imaging system comprises a lighting source, a visible light splitter, an image sensor and a displayer. Visible light from the lighting source is reflected by the light splitting piece and then passes through the second reflector to be incident onto the metal film through the microscope objective, visible light reflected by the metal film passes through the microscope objective, the second reflector and the visible light splitter to enter the image sensor, and the displayer displays images from the image sensor.