Swarm Intelligence (SI) is a relatively new technology that takes its inspiration from the behavior of social insects and flocking an In this paper. we focus on two main SI algorithms Ant Colony Optimization (ACO) and Particle Swarm Optimization (PSO) An extension of ACO algorithm and a PSO algorithm has been implemented to solve the portfolio optimization problem. which is a continuous multi-objective optimization problem The portfolio optimization model considered in this paper is based on the classical Markowitz mean-variance them), The results show ACO performs better than PSO in the case of small-scale and large-scale portfolio. but in the case of medium-scale portfolio. PSO performs a better than ACO technique