A process diagnosis system includes a digital twin calculation unit, a process diagnosis calculation unit, and a remote calculation analysis unit. The digital twin calculation unit obtains a vibration-related parameter and a cutting-related parameter of a processing device, and performs a simulation calculation for the vibration-related parameter, the cutting-related parameter and a three-dimensional model corresponding to the processing device to generate a three-dimensional calculation result. The process diagnosis calculation unit receives a three-dimensional calculation result and displays the three-dimensional calculation result. The remote calculation analysis unit receives the three-dimensional calculation result, and performs a simulation analysis for the three-dimensional calculation result to generate an analysis result.