The method of track optimal synthesis for the adjustable spatial RRSS mechanism for multi-tasks based on Genetic Algorithm is proposed.The mechanism optimization model is established by taking the minimum of square of the error between the actual trajectories and beforehand ascertainable trajectories as the goal function.And the global optimization solution is gained by the Genetic Algorithms.In order to improve the evolutionary speed and accuracy of solutions effectively

a method that can adaptively adjust mutation rate and value according to fitness of individual is used

at the last

a numeric example is given to illustrate the method.