In this paper, the uniaxial compressive strength and shear strength test of frozen soil of the ② ~ ⑤ layer marine sedimentary soft clay for the passway of tunnels in the line 1, Ningbo urban rail transit project are executed. The results show that the mechanical parameters of ② ~ ⑤ stratums are improved greatly after freezing due to the high water content. The uniaxial compressive strength and shear modulus linearly increase with the decrease temperature, but there is a little influence of decrease temperature on the decrease of Poisson ratio. The internal friction angle and cohesion at -10 ℃ increase remarkably in comparison with the undisturbed soil in the soft clay, and the increase of internal friction angle in ③1 sand layer is small.