A new type of profiled horn with contour constituted of three kinds of curves is presented and simulated. Its radiation performance shows good circular symmetry，low sidelobes，low cross-polarization and high Gaussian coupling efficiency. In the frequency range of 39 GHz-42 GHz，the return loss is below -20 dB, the antenna radiation efficiency approaches to 100%, and the coupling efficiency reaches 98%, which is comparable to the performance of corrugated horn. Therefore it can be used as an efficient Gaussian beam launcher to take the place of corrugated horn which is relatively complicated and costly.