Abstract: Taking the solution of nano-magnesium oxide particles as the working medium, experimental study on particle fouling in plate heat exchangers was carried out so as to analyze the influence of particle concentration, particle size, flow velocity and medium temperature on the particle fouling resistance. Results show that the particle fouling in plate heat exchangers has no obvious induction period; both the scaling rate and the asymptotic fouling resistance increase with the rise of particle concentration, in a lowering gradient; the particle size has relatively obvious effect on the fouling resistance; for a fixed mass concentration of particles, the smaller the particle size is, the higher the scaling rate and fouling resistance will be; the influence of flow velocity on the fouling resistances is relatively complex; the scaling rate at a higher flow velocity is slightly greater than that at a lower flow velocity, and the asymptotic fouling resistance is smaller under the former condition than that under the latter condition; the temperature of low-temperature medium has no obvious effect on the particle fouling resistance.