The presence of anaplastic lymphoma kinase (ALK) rearrangement defines a molecular subtype of non-small cell lung cancer (NSCLC). ALK inhibitors (ALKIs) confer significant clinical benefits in patients with ALK-positive advanced NSCLC; therefore, it is of great clinical significance to select accurate, rapid, and appropriate ALK testing methods to screen for patients who are suitable for anti-ALK treatment. In recent years, great progress has been made in the development and clinical application of ALKIs, as well as in our understanding of acquired drug resistance mechanisms. Meanwhile, new ALK companion diagnostic platforms have been developed and applied in clinical practice. Although many studies have shown that there is a high rate of concordance among these platforms, new problems continue to appear during testing. To maximize the benefit for patients, accurate testing results can be obtained by first selecting the appropriate testing method and then formulating, optimizing, and complying with the standardized testing process in accordance with the testing population and specimen types. With the ongoing accumulation of clinical practice data, experience from quality control of ALK testing, and results from multicenter research, an updated expert consensus is necessary. The experts who participated in the discussion and development of this guideline have a rich background in theoretical and clinical testing experience, which ensures the practical value of the information presented in this guideline.