The invention discloses a predicting method of a flexible 
machining surface error of large disc mining cutter plane 
cutting, and relates to the field of prediction of the 
machining surface error. Thepredicting method comprises the following steps of building a single-step analysis standard finite 
element model, extracting an analysis file, building a main circulation analysis step to obtain a node position and an initial value of a flexible main circulation 
cutting force set, initializing a flexible main circulation finite 
element analysis model file to determine instantaneous 
cutting force of a subsidiary circulation cutting position, updating a subsidiary circulation finite 
element analysis model file, conducting finite 
element analysis, conducting flexible 
machining error calculation,judging whether subsidiary circulation of the flexible machining error calculation is converged or not, judging whether the cutting process is finished or not and conducting surface machining error 
point cloud processing to obtain a surface machining error cloud graph. By means of the method, after a large disc 
milling cutter is machined, the whole surface flexible machining error form can be simulated, the plane milling machining error forming mechanism of the large disc 
milling cutter is studied more comprehensively, and a prerequisite is provided for design of the 
machining process and control 
strategy development of the 
machining process.