Learn about how to do if the status bar cannot be pulled down on lockscreen interface
Applicable for all ColorOS 5.2 device. Check your ColorOS version in [Settings] > [About phone].
Go to [Settings]> [Notification and status bar], turn on [Allow drop-down notification bar on lockscreen interface] and you can access to the notification center even when your screen is locked.
* Pictures, settings and paths might differ from those of your phone, but that do not affect the description in this article.