Abstract: Three-position-pumped double-clad fiber lasers are the simplest and essential forms of multi-position-pumped ones with side-pump technologies.In order to obtain higher laser output power under the same pump powers,the optimization of the pump parameters was studied.Firstly,the rate equations of Yb-doped double-clad fiber lasers are applied to acquire the expression of total lost pump power.Secondly,the optimum design model,the analytical expression for choosing the optimum side-pumping position,was obtained based on the principle of minimal total lost pump power for the three-position-pumped double-clad fiber lasers.The simulation results showed that the output power of the optimized double-clad fiber lasers was higher than that of the original ones,especially for the double-clad fibers with large total lost pump powers.The optimization methods are valuable,from which the optimum design for multi-position-pumped double-clad fiber lasers can be derived.