Optimal allocation of multiple-type distributed generators in unbalanced radial distribution systems is proposed in this article. Reduction of system total losses along with voltage profile enhancement represent the objectives of such multiple distributed generator allocation. Three types of distributed generator with different abilities to generate or consume reactive power are considered in this study. Photovoltaic based distributed generator can be synchronized with each phase independently; therefore, single-phase distribution of Photovoltaic is examined in this article. To reduce the searching effort especially with large systems, candidate locations are picked up first depending on a voltage- total real line loss index. Then, sizes of these three types of distributed generator are found by applying crow search algorithm, where a constrained optimization problem with voltage profile and loss indices as the objectives is constructed. The proposed method is applied on IEEE 13-bus, 34-bus and 123-bus unbalanced radial distribution systems. Numerical results realized by crow search algorithm are compared with those obtained by the artificial bee colony method. Analysis of the three systems indicates that the proposed allocation methods are effective in reducing total active power losses and in improving the voltage profile