Prism frame capable of being freely adjusted and accurately positioned on plane

The utility model relates to the field of engineering surveying, and discloses a prism frame capable of being freely adjusted and accurately positioned on a plane. Firstly, the approximate position of a to-be-lofted point is found, then the prism frame is placed on the position, the supporting legs are inserted into the ground, and it is ensured that an instrument foundation is stable and does not shake in the measurement process. Then, through the sliding rail and the sliding block between the first support and the second support, the sliding rail and the sliding block between the first support and the vertical adjusting rod, and the height of the vertical adjusting rod, the spatial position of the prism interface is adjusted in three dimensions including the horizontal transverse direction, the horizontal longitudinal direction and the vertical direction. The first bracket and the second bracket as well as the relative position between the first bracket and the vertical adjusting rod are fixed through the l