The utility model relates to the technical field of crane machines, and discloses a system for detecting pendency height of a hook, and a crane. The system for detecting the pendency height of the hook comprises a crane arm parameter detection device, a winching rope release length detection device, a control device and a display terminal, wherein the crane arm parameter detection device is arranged on a crane arm and is used for detecting the current length and the current variation amplitude angle of the crane arm; the winching rope release length detection device is used for detecting the current rope release length of a winch; the control device is respectively connected with the crane arm parameter detection device and the winching rope release length detection device through signals, and is used for obtaining the current pendency height of the hook according to corresponding relationships of the length of the crane arm, the variation amplitude angle, the rope release length of the winch and the pendency height of the hook, and is used for outputting a signal of the current pendency height of the hook; the display terminal is connected with the control device through signals and is used for displaying the current pendency height of the hook. By adopting the system for detecting the pendency height of the hook, which is provided by the utility model, the security and the accuracy in operating the crane can be improved.