The invention provides a determination method and device for a maximum geophone offset. The method includes: acquiring different single-shot earthquake data in a work area; calculating a root-mean-square amplitude energy value of each path of earthquake data at a selected time window; processing the mean-square-root amplitude energy values and generating new mean-square-root amplitude energy values; carrying out exponential-curve fitting on new mean-square-root amplitude energy values from (N-t+1)th to Nth path and determining the total number of paths received by arrays after fitting continuation through the continuation; determining the average efficiency of changes of the mean-square-root amplitude energy values of earthquake data of adjacent paths and determining comprehensive amplitude energy values according to the average efficiency and the new mean-square-root amplitude energy values; using the positions of the paths with the maximum comprehensive amplitude energy value as the single-shot maximum geophone offsets and taking the positions with the largest number of single-shot maximum geophone offsets as the maximum geophone offset of the work area. The determination method and device for the maximum geophone offset do not require establishment of an earthquake model and take effects of outdoor interference waves and the like on the maximum geophone offset into consideration so that an appropriate maximum geophone offset can be determined and earthquake-exploration outdoor acquisition material of high-quality can be acquired.