The invention provides a single-cutting forming line for building plates; a reshaping apparatus reshapes a building plate so that the building plate enters a cutting portion from a standard position in a standard direction, a groove cutting apparatus performs groove cutting, a tongue cutting apparatus performs tongue cutting, the building plate is then separated and cut by a separating cutting apparatus into multiple individual building plate units, and each building plate unit has a groove and a tongue, providing assembly functionality; a groove saw set and a tongue saw set may be assembled and arranged optionally in different thicknesses and cross section shapes through groove saw blades and tongue saw blades, thereby cutting grooves and tongues different in size and shape. Therefore, the single-cutting forming line for building plates may form a building plate with a tongue and groove to provide assembly functionality by single cutting, the parameters of the groove and tongue such as size and shape can be changed optionally, the steps are simple, the efficiency is high, cutting quality is good, and the line is flexible and easy to use, novel and reasonable in structure and high in practicality.