To reduce the peak side-lobe level of the sparse array pattern effectively and suppress the sparse array grating lobe at the same time, a pattern synthesis algorithm using multi-objective particles swarm optimization (MOPSO) combined with convex optimization algorithm is presented in this paper. We take MOPSO as a global search and convex optimization as the local search to search for the optimal solution. In this search, the optimization variables include not only the weights of the array, but also the positions of the array, which can provide more freedom to control the performance of the sparse array. Simulation of a sparse circular array model of thirty elements reveals that compared with MOPSO algorithm alone, the proposed algorithms which uses MOPSO and convex optimization to optimize the positions and the weights of the array respectively, can obtain the grating lobes and the peak side-lobe level of lower than -19.3 dB at the same time.