An offline programming device includes an input unit that receives input of a plurality of teaching points, a creation unit that determines intermediate point located between adjacent teaching points and creates an operation program for the robot, a simulation unit that simulates a movement trajectory of the robot when the operation program is executed, and a display unit that displays a GUI screen representing the movement trajectory. The GUI screen includes a first display area showing a time series sequence of the plurality of teaching points and a second display area. When an error is detected in the movement trajectory, a section between the teaching points including the point in time when the error occurs is displayed in the first display area according to a first error display method.

A programming method is for a numerical control machine tool system including a mobile terminal, a controller, a robot, and a numerical control machine tool. The mobile terminal is wirelessly connected to the controller configured to control the robot and the numerical control machine tool, and the robot and the numerical control machine tool being configured to work cooperatively to process a workpiece. The method includes: loading, at the mobile terminal, a preset motion model of the robot and the numerical control machine tool, the preset motion model being a plurality of graphical functional modules and a connection between them; receiving a graphical programming instruction for a user to configure the preset motion model using the mobile terminal; and converting the graphical programming instruction into G-code, where the G-code is used by the controller to control the robot and the numerical control machine tool to process the workpiece.