1. It is unnecessary to list some references in this paper due to following two main reasons. First, the linear small deflection theory of beam can be easily found in any standard monography or textbook of strength of materials. Secondly, the governing equation and iteration technique employed in this paper have not been come forth in related references and are presented in this paper for the first time. Although the author did not get a glimpse of the design chart of the Yongjiang Railway Bridge, the author have visited the construction site, and it is a little pity for not discussing with engineering technicians. The physical data, such as river span and altitude difference etc., are estimated by eye, and there are maybe some errors in physical data. The author feels apologetic for all possible misgivings.