Digital filters are devices which allow some frequencies to pass without being altered while completely blocking others. Mainly two types of digital filters are available: FIR (finite impulse response) and IIR (infinite impulse response). FIR filters are used in wide variety of applications due to their linear phase response and stability. Filter designing involves use of traditional non-optimization techniques that provides suboptimal results. In order to further enhance the efficiency of designed filter, a number of optimization techniques have been proposed. Particle Swarm Optimization (PSO) is one of such optimization algorithm. This paper presents a review of FIR filter designing using PSO.