Voluntary performance guarantee in mergers and acquisitions is a unique phenomenon in China，which has become one of the hottest topics among academia and media． However，the research on the voluntary performance guarantee in mergers and acquisitions is rare． From the cost-revenue perspective，this paper introduces game theory into the analysis of this topic． The results show that the likelihood，as well as the amount，of the voluntary performance guarantee increase with the target firms’information asymmetry． The above results are still robust after using instrumental variables in a two stage regression，the PSM test，substituting independent variables，and the two-way clustering test． Further studies show that institutional investors in the target firm can weaken the positive effect of the information asymmetry on both the likelihood and the amount of voluntary performance guarantee． These conclusions may be helpful in bringing some inspirations to governments，listed and target firms，and individual investors．