  PandaX-4T is a dark matter direct detection experiment located in China
jinping underground laboratory. The central apparatus is a dual-phase xenon
detector containing 4 ton liquid xenon in the sensitive volume, with about 500
photomultipliers instrumented in the top and the bottom of the detector. In
this paper we present a completely new system of readout electronics and data
acquisition in the PandaX-4T experiment. Compared to the one used in the
previous PandaX dark matter experiments, the new system features triggerless
readout and higher bandwidth. With triggerless readout, dark matter searches
are not affected by the efficiency loss of external triggers. The system
records single photelectron signals of the dominant PMTs with an average
efficiency of 96\%, and achieves the bandwidth of more than 450 MB/s. The
system has been used to successfully acquire data during the commissioning runs
of PandaX-4T.
