Based on the experience, this paper summarizes the common problems in the online catalogue data of National Library and Shanghai Library, such as the omission of ISBN in the whole field or sub-field in @ d Price, the mistake of RMB currency code "CNY", the error of the sub-field list of the 200-word book title and responsibility, the 2 15 vector field forming an error page of a sub-field, and the omission of the page number but the sub-field size of "A". The size unit cm is incorrectly recorded as "cm", the general account field 606,690, the "CLC" field 70 1 word and person's name-the main responsible person missed and mistakenly recorded, etc., and the treatment method is corrected.