Abstract: The free-floating space robot arm will bring attitude reactions to the spacecraft in target capturing process.For this problem,a new Cartesian trajectory optimization method is proposed.An objective function is established for measuring the variation of spacecraft attitude.This function constrains the angle of each joint within their ranges,and eliminates the influence of dynamics singularity.By the optimization of genetic algorithm,the influence on spacecraft attitude deduced by the Cartesian trajectory tracking motion of the space manipulator end effector is reduced.The simulation results verify the validity of the algorithm.