Example data security processing methods and apparatus are described. One example method includes setting up a first PDU session. A first base station derives a first user plane key based on a received base key and performs security processing on user plane data in the first PDU session by using the first user plane key and a security algorithm. A second PDU session is set up. The first base station derives a second user plane key based on the base key and performs security processing on user plane data in the second PDU session by using the second user plane key and the security algorithm. The user plane key includes a user plane encryption key and/or a user plane integrity protection key.