To improve the spectral efficiency and user experience of terminals at cell edge of LTE-Advanced systems, two improved single frequency network (SFN) precoding schemes were proposed for coordinated multi-point (CoMP) transmission systems based on the existing methods, which can solve the problem of uncertainty when the channels are merged in traditional SFN precoding scheme. The first improved scheme adds a phase parameter to the transmitted end, which is determined by maximizing the channel gain after mergence. The second improved scheme takes a swapping function at some transmission points when the transmitted data is mapped to the antenna ports, and the swapping rule is also determined by maximizing the channel gain. Simulation results have shown that the two proposed schemes can improve the spectral efficiency of users at cell edge in both correlated and uncorrelated channel, and both low and high rank channel.