This paper discusses the improvement of peak resolution of static light scattering particle size measurement by application of modern iterative solvers for ill-posed problems. Static light scattering particle size measurement has many advantages such as wide range, short measurement times, and large number of measurable particles. However, the ability to separate a mixture of two different sized particles is limited. For example, if a sample contains similar sized (about 2:1 or lower ratio of particle sizes) particles, there is a possibility to fail to resolve individual peaks. That is, the obtained distribution will have one peak instead of the expected two. To overcome this disadvantage, we investigated the iterative solvers. In recent years, a number of algorithms for illposed inverse problems have been developed. We tested such algorithms by numerical simulations. In this computing experiment, the MRNSD method showed high resolution for single peak mixture samples. Finally, we measured a mixture of two sizes of polystyrene latex (PSL), 1.6 micron and 3.0 microns and a mixture of three sizes of PSL, 1.6 micron, 3.0 micron and 6.0 micron by light scattering and analyzed the data with the MRNSD method. We also analyzed the samples by image analysis and compared the results.