In order to reduce the decoding error rate of channel transmission under serial interference in cloud network 5G communication environment, a secure control method for downlink channel transmission of 5th Generation Mobile Communication Technology (5G) communication based on asymmetric encryption technology is designed. Establish an optimization equation for 5G communication downlink channel transmission attenuation balance based on the optimal control value, optimal balance index, and optimal control node of the communication channel. Generate secure public keys for channel transmission control nodes based on asymmetric encryption, and decrypt the encrypted data using the public key by combining the attenuation balance optimization equation. Innovatively and dynamically generate the off network transmission control prime number of the 5G communication node in the cloud network, update the private key, so that a public key can correspond to different private keys on different transmission control nodes, and realize the downlink channel transmission security control in serial interference, thus reducing the decoding error probability. The experimental results show that after applying this method, the decoding error rate of the edge server reaches below 10-8, reducing the probability of decoding errors and ensuring that data is not tampered with or damaged during transmission. The data transmission security control effect is relatively good.