The invention discloses a universal type connecting device for an emergency power supply vehicle and a low-voltage overhead line. A connecting device is arranged between the emergency power supply vehicle and the low-voltage overhead line. One end of the connecting device is connected with the emergency power supply vehicle, the other end is connected with the low-voltage overhead line, and circuit connection with an isolation protection function is established between the emergency power supply vehicle and the low-voltage overhead line. The connecting device comprises an insulated cross arm assembly and a switch cabinet. An emergency power supply of the emergency power supply vehicle firstly passes through the switch cabinet and then is connected with the insulated cross arm assembly through a pole climbing cable connected with the switch cabinet, and the pole climbing cable is connected with a circuit of the low-voltage overhead line through the insulated cross arm assembly. The universal type connecting device is applicable to the fields of providing emergency protection, power generation and on-load transformer replacement work for customers along the low-voltage overhead line in a transformer area. The connection is reliable. A power supply effect is stable. The security is good. The universal type connecting device also can match the performance of novel working projects such as replacement of a transformer and a drop fuse under load.