To study the corner effect of the earth pressure for small-sized excavation, the spatial distribution of active earth pressure was studied for excavations with different sizes, using laboratory model test and the FLAC^3d respectively. The influences of L/H (L is the length of primary wall; H is the excavation depth) and L/B (B is the length of complementary wall) on the significance of corner effect were also analyzed. The results show that: the distribution of active soil pressure displays the effect of corners in the depth of 1.5H; the distance affected by the corner effect is almost the same (within 0.2H from the corner) for different sizes of excavations; the shear stress in cement-stabilised soil is greater on the corner section because of the existence of the corner effect; for relatively small L/H, the significance of corner effect is mainly affected by L/H; the significance of corner effect seems to be independent of L/B.