We are interested in tracking human postures by deploying accelerometers on a human body. One fundamental issue in such scenarios is how to calculate the gravity, no matter when human body parts are moving or not. Assuming multiple accelerometers being deployed on a rigid part of a human body, a recent work proposes a data fusion method to estimate the gravity on that rigid part. However, how to find the optimal deployment of sensors that minimizes the estimation error of the gravity is still an open problem. In this paper, we formulate the deployment optimization problem. Since the problem is hard, we conduct experiments to observe what the optimal deployments should be.