Abstract
The radial velocity measurement is a popular method to detect exoplanets in recent year. About 95% of discovered exoplanets were found by this method. According to the periodic velocity variation of the host star, we can predict the possible mass, eccentricity, and semi-major axis of the exoplanets. Through the code SWIFT, the observational data of 16 Cygni B (HD 186427) planetary system is used to predict the possible undiscovered additional planets with the chi-square method. Finally, we check the stability of the system when both detected and additional planets exist and interact each other.