Genetic analysis can provide important information regarding the diagnosis, subtype, and prognosis of lymphoma. There is a growing body of evidence on liquid biopsy using circulating tumor DNA (ctDNA) as an alternative method for genetic analysis. CtDNA is tumor cell-derived DNA that is found unbound in body fluids. CtDNA levels are related to cell proliferation, apoptosis rate, and disease type, and have been shown to correlate with systemic tumor volume. Unlike biopsy tissue-derived DNA, plasma ctDNA is derived from lymphomas across the entire body. Other advantages of ctDNA analysis are that it is less invasive and easy to repeat. It is not only useful for diagnosis and disease typing, but can also be used in prognostic prediction based on the ctDNA level and changes in ctDNA level with treatment, evaluation of minimal residual disease, monitoring for recurrence, early diagnosis of resistance, and early detection of transformation. This method shows great promise for future clinical applications.