For an optimal design of synchronous reluctance motor (SRM), rotor topology and the choice of numerous design variables remain a significant challenge. Generally, the rotor of SRM is only designed in the axial or radial direction, and the design variables are reduced based on experience; however, the above process is time-consuming. In this paper by comparing performances of SRM with different pole/slot combinations and the numbers of flux barriers, the SRM topology with 4-poles/36-slots combinations, distributed windings, and three-layer flux barrier is first proposed. And then, the step-skewed rotor with asymmetry flux barriers and flat tips are adopted. Further, the Taguchi method, differential evolution (DE) algorithm and Pareto evaluation are integrated to implement the sequence subspace multi-objective optimization, the proposed SRM design scheme is obtained. Finally, a 3kW SRM prototype is designed and its FEA (finite element analysis) is carried out to validate the technical advantages of proposed SRM topology and design methods.