Aiming at the problem that the electrophoretic film thickness of the whole vehicle suddenly increased after cleaning the electrophoretic bath,and even there was no electrophoretic film in part of the inner cavity of the chassis frame,the electrophoretic film thickness of the inner cavity of the frame still can not meet the requirements of process quality by improving the electrophoretic voltage and time,etc.After detecting the throwing power of the electrophoretic solution,it was confirmed that the increase of the electrophoretic film thickness was caused by the low throwing power.By adding electrophoretic assistant to improve the throwing power,adjusting the actual control value of electrophoretic solution parameters,etc.,the throwing power of electrophoretic solution was restored to the normal level.At the same time,the electrophoretic film thickness in the inner cavity of chassis frame meets the requirements of process quality.