The method of traditional cumulant is a standard technique used to analyze dynamic light-scattering data. However, the different baseline values influence the results measured by using dynamic light-scattering. A method of moment-cumulant, which fits the baseline automatically, is proposed. The correlation function is used as the model function to inverse the particle diameter and distribution factor pi directly. An experiment is done with latex particle of 90 nanometers in laboratory. Compared with the two cumulant models, it is shown that the particle diameter and particle distribution factor pi are unstable in width fit range and lead to deviation with traditional cumulant, while measurement results is good in stability and not influenced by correlation time with the cumulant method of baseline auto-fitting.