A measurement method comprising: transmitting a plurality of ultrasonic signals to the fluid to be measured; receiving an return signal reflected or scattered from the particles in the fluid under test; calculating a one or more calculated values of the R parameter associated with the particle properties based on the return signal; determining the theoretical curve of the R parameter associated with the particle properties; and determining the mean diameter of the particles in the fluid based on the one or more calculated values of the R parameter and the theoretical curve of the R parameter; determining the mass concentration of the particles in the fluid according to the mean diameter of the particles. Embodiments also provide a measurement system for measuring the mean diameter and mass concentration of the particles.