The invention provides a monitoring method for the turning stability of a digital control machine tool, relating to the monitoring technical field. As the performance of a servo system is continuously improved, a response speed, the sensibility and the like of the servo system are also continuously improved, thus, states of the machine tool can be reflected on a current of a driving motor during a cutting process. In the invention, through various signal processing methods, a plurality of characteristic values of current signals are extracted, a characteristic status vector is established as an input of a mathematical model, and a cutting status of the machine tool is output through analysis and calculation of the mathematical model. As the invention has the characteristics that the current signal has high anti-interference performance and is easy to be acquired, assistant tools are fewer, and the like, compared with a plurality of existing monitoring methods, the invention has the advantages of simple and feasible operation, good monitoring effects and the like; thereby, the invention can more easily realize the online monitoring for the processing states, and can effectively guarantee the processing security and the product quality.