Since 1980s, China has begun to study sea ice in the polar regions, and more accumulation has been made in the natural science of the sea ice than in the relevant engineering application. The engineering properties of the sea ice are of great concern with the increasing value of polar shipping. The physical and mechanical properties are important engineering properties of the sea ice, which determine the rational design and safe operation of the ice engineering. The three-point bending tests under different temperatures are conducted in the low-temperature laboratory to measure the sea ice flexural strength and effective elastic modulus by using the complete ice block that was extracted through the whole ice thickness of the landfast sea ice in the Prydz Bay during the 36th Chinese National Antarctic Research Expedition. The flexural strength and effective elastic modulus are correlated to the sea ice porosity. The lower envelope of the flexural strength and the upper envelope of the effective elastic modulus are used to estimate the bearing capacity of the landfast ice in the Prydz Bay, Antarctica. It can provide a safety guarantee for the unloading on ice in Antarctica. By using the physical properties of the sea ice, the mechanical properties of the sea ice are obtained to design the bearing capacity of the ice layer, which gives a new insight on the ice engineering.