Pilot coverage optimization is an important issue in daily operation of cellular networks. It is difficult to meet the various coverage requirements in practice using existing framework such as adjusting antenna downtilts or transmit powers of sectors. In this paper, a novel coverage optimization method based on multi-sector joint beamforming is proposed to eliminate poor coverage and to minimize interference to the surrounding sectors. A heuristic algorithm is developed based on the iteration of sector coverage updating and antenna array excitation weights optimization. Numerical results show that the performance of our algorithm is superior to that of power exhaustion algorithm.