Abstract: The post-processor serves as a critical bridge between computer-aided manufacturing （CAM） and CNC machining, with its performance directly influencing machining accuracy and efficiency. This study develops a post-processor for the Heidenhain iTNC530 system based on the PowerMILL Post Processor Editor, aiming to achieve automated generation of the PLANE command for complex multi-axis machining tasks. The workflow is elaborated in detail, including tool orientation vector extraction, rotation angle calculation, and PLANE command generation, supported by a case study demonstrating the application of mathematical models and rotation matrices for optimized toolpath control. Simulation verification confirms that the developed post-processor generates high-precision NC programs, enhances machining automation and stability, and provides practical guidance and technical references for post-processing development in multi-axis machining.