The invention discloses a three-dimensional cross line laser. Four vertical line projection windows which are evenly distributed at 90 degrees are arranged on the upper portion of a machine body, a horizontal line projection window is arranged exactly on the front face of the machine body, a circular arc line projection window is arranged exactly on the rear face of the machine body, and a spherical face prism is arranged on the inner side of the circular arc line projection window. A laser source projects lines through the spherical face prism to form circular arc projection lines, by means of cooperation of the horizontal line projection window and the vertical line projection windows, an independent three-dimensional measuring line projection effect is achieved, universality and practicality are enhanced, measurement data is accurate and efficient, using is flexible and operation is easy and convenient.