A soft building block assembly includes at least one soft building block element formed by soft material and having at least one buckling portion; by stacking of the soft building block element elements, various kinds of toys being formed; a Shore value of the material of the soft building block element is between 20 to 95. Material of the soft building block element is selected from one of PE(Thermal Plastic Elastomer), TPR(Thermal Plastic Rubber), TPU(Thermal PU, PU(Polyurethane) or thermal static material, such as silica rubber. the soft building block element has at least one of a buckling portion and a coupling portion, and the buckling portion of a soft building block element is buckled to the coupling portion of another soft building block element.