The application process of upgrading the coating pretreatment production line from powder surface conditioning to liquid surface conditioning was Introduced,including on-site preparations and economical budget.At the same time,according to the technical problems and solutions faced in the upgrading process,the matters needing attention.of liquid surface conditioning was obtained.Finally,according to the field application results,the original economic budget was revised to provide more instructive guidance for the application and promotion of subsequent liquid surface conditioning working direction.