The invention relates to the technical field of arrester installation, in particular to an electric portable arrester diagonal draw bar installation device and method. The device comprises a transmission mechanism, a rotating shaft and an annular fixing part. The transmission mechanism and the rotating shaft are correspondingly connected through the annular fixing part. The transmission mechanism provides rotating power through a handheld electric screwdriver. The rotating shaft is correspondingly connected to the clamp position of an arrester diagonal draw bar. By the adoption of the structural arrangement, assembly of a clamping part and an epoxy sleeve in the arrester diagonal draw bar can be achieved by means of cooperation of the transmission mechanism, the rotating shaft and the annular fixing part of the device, working efficiency is improved, and the device is portable, simple and practical.