Abstract: The problems of shape design and position arrangement for water strider robot's supporting legs are discussed. Firstly,the supporting leg is regarded as Euler-Bernoulli elastic curved beam and a method for designing its optimal shape is proposed by analyzing its geometric flexible deformation and stress-strain.The objective of the optimal method is to attain the maximum supporting force.The effectiveness and validity are verified through simulations and an experiment. Secondly,a method for arranging the supporting legs on the robot body is proposed by analyzing the influence of supporting legs' spacing on supporting force,and study the relation between supporting legs' position arrangement and robot's rolling-resistant capability.A layout scheme for the Water DancerⅡ-a with ten supporting legs is designed,which satisfies the requirements.