A laser instrument is designed to measure tunnel surface, which use a laser distance measure component as measuring sensor. The surface of the tunnel shape and the outline of the object can be measured by the instrument which can rotate around two axes mutually perpendicular. The measure data is processed and the graphic of the surface shape is generated. The hardware structure and composition of the instrument are analyzed, the hardware circuit is designed and components are chosen. Hardware control software and data process procedure are designed. The actual surface can be measured to draw out the 3D graphics. The advantages of this instrument are verified that has stable performance, quick measuring and convenient to use in practices.