Teed connecting parallel transmission lines frequently subject a variety of technical problems in the view of protection engineering. These problems are mainly due to the mutual coupling between lines and the multiple branch of teed connection, which requires choosing faulted branch before fault location. A new accurate fault location algorithm for parallel transmission line with a teed connection is introduced in this paper. Depending on six-sequence fault component method, the coupled transmission equations are transformed into decoupled ones. Based on the detailed analysis of peculiar characteristic of teed connection, the differential positive sequence component measurement, which is one of the six-sequence fault components, is used to implement fault location for parallel line with a teed connection. The new location algorithm makes full use of the decoupled mode and the teed structure. It is independent of source impedance, fault type, fault resistance and mutual coupling between parallel lines. The algorithm has been tested by EMTP simulations, which indicates that this location method obtains high accuracy under various fault conditions.