Abstract: This paper describes the design and realization of a software aimed at the demands of astronomical observation of the FAST. The paper first gives an analysis of software requirements based on the principle of FAST observation. We then proposes an algorithm for planning celestial track(s) of the feed source, and present the design and implementation of the control software for astronomical observation. We show simulations of celestial tracks observed with the software. Finally, with experiments on the 40m model of the FAST, we verify the feasibility of the algorithm and the software.