[Objective] To overcome defects on index of "interception rate" and "actual interception" in study of intercepting rainfall of forest canopy. [Methods] The conception on interception capacity of forest canopy and approximate determination way were posed. Through the actual data

approximate determination way and mutual comparison of two stands were introduced further for interception capacity. [Results] The conception of interception capacity can better reflect effect and degree of forest canopy intercepting rainfall. The comparison of interception impact between different stands (or tree kinds) not only was made by means of interception capacity

but also was not restricted by regions. [Conclusion] The interception capacity is an effective and rational index on comparing the interception impact of rainfalls among different stands.