Proppant particle transport in a tortuous fracture is a common but poorly understood element of hydraulic fracturing. An experimental investigation is conducted in a narrow, tortuous slot with two 90-degree bends while flowing four particle types. These results confirm that particle transport mechanisms in a tortuous slot are more complex than a straight slot. The phenomena of particle vortices and resuspension were observed near bends. As a result of vortices, two depressions are near the bends, and a three-step, terraced profile of the bed is formed. There is a natural logarithmic correlation between the depression height and Stokes number. The fluid velocity is the primary factor affecting the proppant transport, followed by particle density and size. The hindrance effect on particle settling would be significant at low fluid velocity. This study provides fundamental insights into understanding particle-fluid mixture flow in a tortuous fracture. (C) 2020 Elsevier B.V. All rights reserved.