Background: For EGFR-mutant advanced non-small cell lung cancer (NSCLC) patients, EGFR- tyrosine inhibitors such as gefitinib, erlotinib, and osimertinib, are recommended as the preferred first-line treatment. Unfortunately, relevant drug resistance is often inevitable and for first and second generation EGFR-TKIs, drug resistance most commonly (50-60% of cases) occurs at the secondary point mutation T790M. Second-line treatments may include administering the third generation of EGFR-TKIs, such as osimertinib and almonertinib. In a few relevant studies, rearrangement of the anaplastic lymphoma kinase (ALK) gene was detected in patients with T790M mutation after drug resistance to osimertinib re-occurred following administration as a second-line treatment. The studies concluded that ALK rearrangement is a rare but critical drug resistance mechanism for osimertinib. However, to date, it remains unclear whether almonertinib also triggers the same ALK rearrangement. The current case study is the first one detailing the detection of an ALK rearrangement after almonertinib resistance in advanced EGFR-mutant NSCLC, which contributes to the limited body of literature examining ALK rearrangement as a mechanism of resistance to EGFR-TKIs in advanced EGFR-mutant NSCLC.Case Description: Herein, we present a 35-year-old female patient with EGFR-mutant advanced NSCLC in the last trimester of pregnancy. The patient was administered multiple treatments, including first-line icotinib and second-line almonertinib. According to the next-generation sequencing (NGS) assay after almonertinib resistance, the development of an EML4-ALK fusion mutation was considered to be a potential mechanism of almonertinib resistance. Subsequently, the patient received a combination of almonertinib and crizotinib, and at the last follow-up, the treatment showed a curative effect and then maintained a one-month stable disease.Conclusions: This case report suggests that ALK rearrangement may be a potential mechanism of almonertinib resistance. The combination of ALK TKI therapy and EGFR TKI may be a viable strategy for almonertinib-resistant NSCLC patients induced by ALK rearrangement.