In order to identify the immune effect against classical swine fever virus（CSFV）and its trend in scale swine farms，22 465 serum samples were collected from 717 scale farms in 16 cities from 2011 to 2019 to detect the antibodies against CSFV by ELISA，and the immune levels in different years and farms were compared. The results showed that，for breeding farms，the immune qualification rate at farm/herd and individual level were 73.84% and 77.54%，respectively；and for commercial farms，the rates were 63.96% and 71.79%，respectively. In different years，the level of CSFV immune antibodies varied in a wave way，specifically，remained higher during 2011 to 2011，turned lower during 2013 to 2014，went up again during 2015 to 2016 and then decreased during 2017 to 2019；for different farms/premises，breeding farms were better than commercial ones in terms of the immune effect no matter at individual or herd level. It was concluded that the overall level of immune antibodies against CSFV was relatively low and unstable across Shandong province. Therefore，the immunization and surveillance of CSFV should be further strengthened in scale farms，especially the commercial generation pigs，with a view to reducing any risk of outbreak.