The invention discloses a safety access method based on channel detection and user QoS. The safety access comprises the steps: performing channel detection by use of an artificial neural network (ANN), determining whether the system capacity is redundant, and realizing physical layer safety transmission under the condition of satisfying the statistics delay QoS, wherein each of a sending end, a receiving and an eavesdropper adopts multi-antenna, a signal is sent by the sending terminal through safety encoding and channel encoding; the receiving end firstly performs channel decoding and then performs the safety decoding after receiving the signal; the channel prediction is performed at a transmitting end Alice so as to decide whether to adopt the safety encoding under the condition of satisfying the delay Qos. By use of the safety access method disclosed by the invention, the maximum safety transmission capacity can be provided under the condition of selecting the optimal physical layer security when the delay QoS is guaranteed.