Baltic Dry Index (BDI) is one of the major indexes for international commercial trade,and these years,China's fast growing Gross Domestic Product (GDP) enables its more powerful emphasis on BDI.Thus,the attraction force of China's GDP across BDI was studied.The BDI and GDP's changing tracks were fitted by different functions and their attraction relationship was explored through calculus analysis for determining the corresponding attraction force.The attraction mentioned above was used to rebuild the BDI corresponding to the GDP data,and the GARCH model for contrast was introduced then.Meanwhile,in the research,the random interference was also taken into consideration.The conclusions indicate that China's GDP indeed attracts BDI,which may provide a cogent method for economic crisis study.