We propose a deterministic SWAP gate for dual-rail-encoded single photon qubits. The gate is constructed from waveguide crossings, Mach-Zehnder interferometers and phase shifters which provide the gate reconfigurability. Through manipulating the phase of the phase shifters, we can apply either the SWAP or identity gates. As an essential element of nearest neighbor qubit networks, the SWAP gate has a simple structure and presents minimal overhead. Providing an efficient solution to the geometric restrictions of on-chip dual-rail qubit circuits, our design may be utilized in applying large scale arbitrary unitary transformations.