Abstarct: Quantum cellular automata (QCA) represents an emerging technology at the nanotechnology level. There are various faults that may occur in QCA cells. One of these faults is a single electron fault that can occur in the process of producing or the operation of QCA circuits. The behaviour of the single electron fault in QCA devices is not similar to either previously investigated faults or conventional CMOS logic. The results show that single electron fault in the majority gate for some inputs is defective and the output obtained is not desirable. The fault rate for the majority gate is %50, Hence half of the inputs do not have the correct output. For other gates, including the NNI and AOI gates, electrostatic energy calculations for different inputs and different positions for single electron in an fault cell were performed. The results show that for some inputs, the output is not correct and the output has a defect. The fault rate for the NNI gate is equal to %0 and for the AOI gate there is a different value depending on the fault cell position. There is also a single electron fault with a new approach to quantum wire. In this case, the single electron fault occurs simultaneously in two adjacent and non-adjacent cells. The results indicate that if this fault occurs, the output of the wire has not changed and fault rate is equal to %0. In the following, new structures are designed from the majority gate that have thirteen cells, nine cells and six cell. These structures have more tolerant of single electron fault and in different pulse approaches the results are reported.