Fault-tolerant machines have attracted extensive attention in the field of machines all over the world for their high reliability， strong fault tolerance and strong ability for operation in harsh environments， therefore， deep researches are carried out focusing on their working principles， topologies， electromagnetic properties and control strategies. It can be found that this type of machine is very suitable for all-electric/more-electric aircraft electrical actuator systems. This paper analyzes and summarizes the key technologies of fault-tolerant machines for electrical actuator system from two aspects： Topology and control strategy. In terms of topology， the effects of each prototype machine on the original electromagnetic performance after introducing fault-tolerant design are compared， and the general design method and general law of fault-tolerant design of the machine are summarized. In terms of control strategy， the inside relations， advantages and disadvantages of two methods based on current vector reconstruction and voltage vector reconstruction are analyzed， furthermore， the torque impulse balance control of fault-tolerant machine for the speed performance improvement is investigated. The simulation and experimental verification are carried out for the classical topology and fault-tolerant algorithm. This paper summarizes the research prospect and application development of fault-tolerant machines， which offers references for the theoretical research and industrial application of fault-tolerant machines.