Abstract： Aim To comparatively analyze the detection of ALK fusion gene in non-small cell lung cancer(NSCLC)using immunohistochemistry(IHC),fluorescence in situ hybridization(FISH),real-time quantitative polymerase chain reaction(qRT-PCR).Methods A total of 453 NSCLC specimens were collected.Forty specimens with different levels of ALK fusion gene ex-pression detected by IHC[ALK(-),(+),(2+),(3+),10 specimens each]were randomly selected.FISH and qRT-PCR were employed to detect the expression levels of ALK fusion genes,and consistency analysis was conducted.Results When comparing the results of ALK fusion gene detection between IHC and FISH/qRT-PCR,the concordance rate for IHC ALK(-)/(3+)with FISH and qRT-PCR was 100％,demonstrating high consistency(r=0.781,r=0.740,P＜0.05).The concordance rate between FISH and qRT-PCR was 97.5％,showing high consistency(r=0.943,P＜0.05).Conclusion There are variations in the results of ALK fusion gene detection among samples with different expression levels using FISH,qRT-PCR,and IHC methods,with IHC demon-strating higher sensitivity.FISH and qRT-PCR show high consistency in the detection of ALK fusion gene samples.