In the field of geodesy, it is common that engineers need to produce 360° circular collimated beam. Now, the scheme is collimating beam from semiconductor laser firstly. Then, projecting the collimated beam to a cone with a inclination of 45° and 360° circular collimated beam comes out. To solve existing problems such as complex structure, inconvenient installation and so on, a design of free-form reflector is proposed to make the whole optical system consist of semiconductor laser and reflector only. The first step is calculating discrete coordinates of freeform by establishing a differential equation in the case of assuming the source to a point source. Then fitting to a freeform surface with the discrete coordinates as above. At last, carrying out a optimization design in the software according to the actual size of source. Then the free-form surface will be obtained with the discrete coordinates as above. Finally, lighttools is used to optimize the optical system according to actual size of light source. The simulation reveals that semiconductor laser with 20° divergence, 50 mm radiusand 30 mm focus can obtain uniform beam of 30 mm width 10 m away.