The embodiment of the invention relates to the field of electroencephalogram signal processing and brain-computer interfaces, and provides a high-signal-to-noise-ratio dry electrode electroencephalogram signal acquisition system which comprises a rigid-flex active electrode device and an electroencephalogram signal multi-stage conditioning and amplifying device. The rigid-flex active electrode device is inserted and interconnected through the electroencephalogram signal multi-stage conditioning and amplifying device by adopting a high-density and ultralow-height plate connector. And through active signal following and step-by-step conditioning and amplification, the signal quality and reliability of electroencephalogram signal acquisition are improved.