Abstract: Series LLC， which sets up a number of series companies with independent right and liability inside the LLC， appeared in Delaware of USA in 1990s. As a special formation of LLC， the legislation of Series LLC shows some different features in terms of its formation， management， distribution of interests， assumption of liabilities and dissolution. The scholars in USA think it can not only separate assets and liability， but also save related fees and taxes and improve the management efficiency， and its disadvantages of uncertainty in terms of tax and bankruptcy can be resolved by the amendment of LLC Law.