To effectively solve large-scale optimization problems, the paper proposes a distributed agent computing framework based on the parallel particle swarm optimization (PSO). The framework uses a master swarm for evolving complete solutions of the problem, and uses a set of slave swarms for evolving sub-solutions of the subproblems concurrently. The master swarm and slave swarms alternatively implement the PSO procedure to improve the problem-solving efficiency. Using the asynchronous team based agent architecture, a master/slave swarm consists of different kinds of agents, which share a population of solutions and cooperate to evolve the population, such as initializing solutions, moving particles, handling constraints, and decomposing/synthesizing sub-solutions. The framework can be used to solve complicated constained and multiobjective optimization problems efficiently. Experimental results demonstrate that this approach has significant performance advantage over two other state-of-the-art algorithms on a typical transportation problem.