Abstract: To investigate the differences of co-occurring woody species with different growth forms when subjected to soil drought, proline contents were assessed in four co-occurring seedlings of Quercus liaotungensis, Fraxinus rhynchophylla, Spiraea pubescens and Lepsedeza bicolor which were subjected to soil drying. The drought-induced increase in proline content was more in old leaves than in young leaves, and was more in roots than in stems and leaves. The proline contents were increased more in the first two species than in the last two ones. Based on the differences in both proline content and soil water content during soil drying, the drought resistance can be ranked as follows..Q, liaotungensis,F, rhynchophylla, S. pubescens,L, bicolor. The findings here suggest that growth form may be related partly to different responses to environmental stress.