A large side-mounted model of gear measurement mechanism was proposed

and the main error sources and features of measurement precision were analyzed. A grey dynamic prediction method was presented to deal with multi-impact factors coupling. Firstly

the error sources influenced tooth profile measurement precision were analyzed and demarcated according to the characteristics of measurement mechanism

and then the sensitivity coefficients of various error sources were calculated. Secondly

the limited error source data were separately resampled

and a grey generation operation was given; the measurement results affected by each error source were calculated in the resampling process; then the error coupling results could be obtained in the error synthesis process. Finally

the measurement precision of large gear tooth profile could be improved greatly by removing the coupling effect existing in measurement result. Compared with the measurement results obtained by the three-coordinate 0.5μm precision measurement machine

the experiment results show that the measurement system presented can meet the measurement requirement of tooth profile for large gear of three-level precision above.