The kinematic performance of stone-carving robotic manipulators（SCRMs）is quite complicated in its workspace,and it has been a important factor affecting the stone-carving products.The kinematic performance of SCRMs in its workspace was analysied and optimized.The kinematics model of SCRMs was established based on the Denavit-Hartenberg (D-H) method,the forward and inverse kinematics solutions of SCRMs were deduced by using the exponential product formula of spinor theory;based on the frobenius norm of Jacobian matrix,the dexterity index which can quantitatively describing the kinematic performance of SCRMs was presented,and the changing rules of the dexterity index in space of joint coordinate and operational coordinate were studied;based on the Dijkstra optimization theory,the optimal workspace for SCRMs was chosen in the reachable workspace.The results show that the fluctuation of joint angular acceleration is greatly reduced when SCRMs moves in the optimal workspace.The results can provide reference for the layout of machining position of SCRMs.