Theory and earthquake induced damage show that the hoist room frame on intake tower of hydroelectric power station are more vulnerable to earthquake damage due to the whiplash effect. In this paper, the intake tower and the hoist room frame were simplified into two distribution parameter beam models by analysis of the basic mechanical characteristics of intake tower, and then the frequency equation was derived using analytic methods. After statistics of hoist room frame and tower height range and according to the principle of equal bending stiffness, the hoist room frame column was equivalent to a single section of the tower fasting column, then the vibration amplitude ratio and frequency distribution of six kinds of models under conditions of different height ratios and different stiffness-mass ratios were analyzed to get the influence rules between each other. The analysis showed that the height of the upper structure had greater influence on the vibration amplitude ratio of first modal shape, and smaller influence on the stiffness ratio, but the stiffness ratio was more significance. Compared with numerical analysis, structural vibration type and frequency by analytic results was relatively consistent with numerical results, verifying the correctness of the above procedure, and indicating that the analytical method for solving such fundamental mode structure was simple and effective.