To analyze the clinical characteristics of null point (NP) in patients with the light cupula. Methods: Twenty-eight patients with light cupula diagnosed by Supine-Roll test were included in this study. All patients underwent videonystagmusgraphy to observe the characteristics of their dynamic positional nystagmus, and to find the nystagmus disappearing plane, that is, the NP, to make a lateralization diagnosis. All patients were followed up to assess the effects of manual reduction treatment. Results: In the 28 cases, 11 (39.3%) presented with spontaneous nystagmus, 10 (35.7%) had NP1, 28 (100%) had NP2 and NP3. Moreover, patients had a good tolerance to NP2 evaluation. The effective rate was 7.1% after first-time manual reduction, 14.3% at one-week follow-up, and 100% at one-month follow-up. Conclusion: The evaluation of NP2 is a simple and effective method for the diagnosis of the light cupula and the lateralization diagnosis. The patients with light cupula have poor response for manual reduction treatment. However the course of disease is mostly self-limiting