Sector fund is now in the fast growing stage. In this research, we use efficient frontier to build up optimal portfolio from 2003 to 2012 via MSCI World Index and sector funds categorized by Lipper Global; by doing this, we can prove that through combining a global wide index with sector funds, the performance measured by Sharpe ratio can be improved. Further, we pick the top three AUM sector funds to construct a portfolio. We determine the weight of allocation among each sector by the past 1, 3 and 5 year, and use the results to invest in the next year. The study concludes that invest by allocating the fund with 3 and 5-year-weight, the return and Sharpe ratio of the portfolio is enhanced.