Aiming at the problems of low positioning accuracy,difficult search and long time consuming for underwater robot to capture objects by robotic arm in deep water,a multi-strategy improved sparrow search algorithm based trajectory positioning method for telescopic arm of underwater robot was proposed.The telescopic boom model was built based on D-H parameter method,and the inefficiency of the telescopic boom in capturing target objects under water was analyzed by combining MATLAB and ADAMS.The idea of birds foraging in the optimal position in sparrow search algorithm was introduced,and Logistic chaos mapping and Cauchy Gaussian variation principle were introduced.The optimal results were analyzed through the four performance indexes of the underwater vehicle.The results show the optimized sparrow algorithm is superior to other algorithms.Compared with particle swarm optimization algorithm,beetle swarm optimization algorithm and whale optimization algorithm,the track route of telescopic arm capturing target is more accurate and the obstacle avoiding is more obvious in water environment.