The dynamic stability issue of West Inner Mongolia Power Grid becomes increasingly severe. To solve this problem, the paper uses "single machine-infinite bus" system as an example for analyzing the mechanism of low frequency oscillation of the system. Aiming at the dynamic stability issues of West Inner Mongolia Power Grid, it proposes the solutions to lower frequency oscillation of the system, including improving power grid structure, adjusting power transmission mode and optimizing parameters of PSS. Using dispatching data of power grid to do simulation calculations, this paper analyzes the proposed solutions. The calculation results show that the proposed solutions have pronounced effect on restraining the low frequency oscillation of Power Grid, can efficiently improve the dynamic stability of Power Grid, and are actually operational in engineering. Finally, in combination with actual issues of investment and duration in engineering construction, this paper gives the brief comparison and selected advices on all solutions above.