Levelling instrument

The invention relates to a levelling instrument comprising a housing having at least one first surface in a horizontal or vertical direction and a machine core. A bulge is arranged on the first surface and is provided with at least two light emitting surfaces connected with the first surface, and each light emitting surface is provided with a first light emitting port. The machine core arranged inthe inner cavity of the housing comprises a self-balancing support, a first laser generator that is arranged on the self-balancing support and is used for emitting a first laser beam which is perpendicular and points to the corresponding first surface, and a first lens which is arranged on the self-balancing support and is located at the end, close to the first surface, of the corresponding firstlaser generator so as to change the direction of the first laser beam to sub-laser beams which are emitted from the at least two first light emitting ports respectively and are parallel to the firstsurface. According to the l