Adopting palm as a reinforcement material which was added into shanghai clay,the paper carried out direct slow shear test so as to study the effect of palm on the strength characteristics of Shanghai clay by changing the reinforcement ratio and palm size of reinforcing material. The results show that ① Compared with the pure soil, the reinforced soil shear strength and cohesion are improved significantly, but angle change of internal friction is smaller. ② The shear strength of size of 4mm×12mm is bigger than that of the size of 4mm×4mm,4mm×8mm and 4mm×16mm，and the optimal rate of reinforcement is 0.5%. ③ When the vertical load is small, the stress-strain curve possesses strain softening.But with the increase of vertical load , the stress-strain curve is strain hardening. ④ Compared with pure soil,the residual strength of reinforced soil is reduced , and its capicity of resistance deformation is enhanced. Therefore, the palm can be used as an effective material for reinforcing Shanghai clay.