Abstract: This paper describes the FORTRAN programs of initial-orbit calculation for asteroids with the improved Laplace method and Gaussian method. The comparison to the JPL DE405 solar system ephemerides shows the effectiveness of the main subroutines. The results of the two programs gives also show that both Laplace and Gaussian methods can be used effectively only with the long-time interval observations such as those in days. In order to predict the directions of asteroids using three directional observations in one day, we find a way to further improve the program of the Laplace method by adjusting the right matrix of the iterative equation and adding some judgements to search out ideal settings. The paper finally gives the test results with the data from the Minor planet and Comet Emphemeris Service as norms. The adjusted program can be used to guide observation based on data in a single day.