Due to the big discrepancy between onshore and offshore oilfields, the development of cyclic steam stimulation in offshore oilfields appears to be more complicated. And a reasonable choice of steam injection volume has attracted increasingly wide attention.Based on the heavy oil reservoir in Bohai oilfield, a numerical simulation model of cyclic steam stimulation was built based on the characteristics of offshore oilfields. The numerical simulation was used to optimize the cyclic steam injection volume. First, seven kinds of programs were designed on steam injection slug size for qualitative research. For the best result, twelve kinds of programs were designed for quantitative research. The results show cycle steam injection volume should be increased with increasing number of cycles,and the increasing rate of each cycle steam injection is 20% with best results. The results can provide theoretical guidance for cyclic steam injection volume optimization of steam huff and puff in offshore oilfields.