Today, the use of CMOS technology for the manufacture of electronic ICs has faced many limitations. Many alternatives to CMOS technology are offered and made every day. Quantum-dot cellular automata (QCA) is one of the most widely used. QCA gates and circuits have many advantages including small size, low power consumption and high speed. On the other hand, using special digital gates called reversible gates, a series of reversible circuits can be built that have their own advantages and applications in digital design. Reversible circuits can be implemented by QCA gates. One of the most important reversible gates implemented by QCA gates is QCA1 gate. In this paper we proposed a reversible full adder using QCA1 gates. Then, proposed reversible full adder is improved to the fault-tolerant structure. This structure has better indexes such as area and latency than similar ones. Reversible circuits are a kind of intelligent systems; because the possible system error can be distinguished by the output values.