The surface velocity structure can be estimated by inverting the dispersion curve extracted from the dispersion image result of the Rayleigh-wave information in shot gathers of near-surface exploration.The dispersion image results from the difference of Rayleigh-wave data in different offset ranges,and will affect the extraction and inversion results of the dispersion curve.In this paper,the authors studied the dispersion imaging results in different collection arrangements and offsets by dispersion imaging resolution and continuity using box wave in LJ area of the Shengli oilfield,and found that the long collection arrangement can improve the dispersion imaging resolution effectively,and that the dispersion imaging result in near offset is better.The authors also tested and verified the effectiveness and applicability of the optimum offset formula proposed by Zhang in 2004,and the results show that it can be used as a standard of the optimum offset in near-surface Rayleigh-wave exploration.