Abstract: In 2020, 5G will gradually enter the stage of large-scale deployment and commercial use. 5G is facing new security challenges and risks while opening up a new situation of Internet of everything. 5G uses new technologies including NFV / SDN, network slicing, cloud computing, MEC to meet the diversified needs of vertical business scenarios. Compared with traditional networks, 5G is more complex, open and flexible. The introduction of new technologies will be accompanied by new security risks and challenges. This paper analyzes the security challenges and security demand that new technologies will bring to 5g, and gives corresponding countermeasures based on the technical characteristics.