The invention discloses a method for determining optimum topological forms of skeleton structures on basis of non-probability reliability. According to the method, uncertain parameters of structures are considered and an MMA algorithm is combined to optimize target functions of structure responses (such as displacement, stress, structure weight and the like), so as to determine optimum structure sizes. The method comprises the following steps of: firstly establishing a reliability index by utilizing a non-probability theory; replacing target reliability by the non-probability reliability index; and finally carrying out iteration by combining a method of moving asymptotes to find a globally optimum value, so as to finally obtain an optimum topological form of a structure.