Dissipative particle dynamics simulations are applied to investigate co-micellization behavior for binary mixtures of Poloxamers in dilute aqueous solution. In view of block length similarity/dissimilarity, four representative mixture cases are considered: F127/P123, F127/P105, P123/P84, and F127/L64. With appropriate interaction parameters, the simulations enable us to examine the formation of micelles, their types, size, shape, and composition. In the investigated concentration range, we find that pure and mixed micelles, both ellipsoidal, always coexist for all cases. At similar concentrations, both species form pure micelles of their own together with mixed micelles. In the case of F127/L64, it is found that the L64 chains are involved in the mixed micelles, even when the L64 concentration is below its CMC. The fraction of L64 involved in the mixed micelles is lower as compared to the other systems studied. For all cases, the proportion of mixed micelles can be increased when the two polymer species have similar concentrations. Moreover, shorter chains may prefer to straddle the core and corona in the region of ellipsoidal interface that is closer to the center of mixed micelle.