A Femto base station (BS) is connected to operator's network using a residential DSL or cable broadband connection and provides service in the licensed spectrum. When a BS operates with time division duplex mode (TDD), synchronization of the transmission time at the BS is important to avoid inter-slot interference with adjacent BSs. Because femto BSs are generally located indoor, they may not receive the global positioning system (GPS) signal which is used to synchronize the wireless cellular network. We propose a multi-hop based network synchronization scheme for femtocell systems. In the femtocell system, synchronization can be achieved by aligning its frame start point with the neighbor cell's preamble signal hop-by-hop. We evaluate the performance of the multi-hop synchronization and compare it to the single-hop synchronization.