Invasive neural electrodes promote human understanding of neuroscience to the micrometer and millisecond scale. Brain-computer interfaces and deep brain stimulation reflect the application value and research significance of neural electrodes. Due to the large mechanical mismatch between traditional rigid electrodes and soft brain tissue, flexible electrodes have become the new trend of neural electrodes. The flexibility of the neural electrode reduces the immune response while losing the implantation stiffness. This review will analyze the implantation mechanism of the neural electrode and summarize the current research on the implantation strategies of the flexible electrodes, which aims to help solve the loss of implantation ability of flexible electrode and remove the obstacles of the flexibility development trend of the neural electrodes.