The invention discloses a detection method for A, B, J subgroup avian leucosis viruses in an avian infectious laryngotracheitis live vaccine. The detection method comprises the following steps: diluting a commercial avian infectious laryngotracheitis live vaccine by adopting DMEM, then inoculating DF-1 cells, acting for 1 h at the temperature of 37 DEG C, then changing into DMEM containing 1%FBS, and culturing for 7 days; collecting cell culture supernatant, and carrying out avian leucosis virus p27 group specific antigen ALV-p27 detection; collecting cell cultures for an ALV-p27 positive sample and extracting cDNA, identifying A, B, J subgroup avian leucosis viruses by adopting a subgroup specific primer, and carrying out IFA detection on corresponding positive porocytes of the A, B, J subgroup avian leucosis viruses by adopting a subgroup specific monoclonal antibody. The detection method disclosed by the invention can enable live viruses to be proliferated in cells, makes up the defects of direct PCR detection and also has the characteristics of effectiveness, accuracy, reliability and the like and great significance on prevention and control of avian leucosis.