Abstract: Autofrettage in outer sleeves is used to improve carrying capacities ofhydraulic coupling. Linear hardening model is used for residualstresses after autofrettage pressurization and after autofrettagedepressurization. It isindicated that the best ratio of external radius to inner radius relates notonly to the yielding limit, elastic modulus and linear strengthening elasticmodulus but also to Bauschinger effect factors. The calculated resultsfor the sizes given by CB*3235-84 shows thatcompared with non-autofrettaged ones, carrying capacities ofautofrettaged outer sleeves increases by nearly 50 percent.