Abstract: An oscillating positive expiratory pressure device includes a housing, a top cover, and an oscillating unit. The housing includes a bottom wall and a surrounding wall. The bottom wall has an inclined enclosing surface extending downwardly and terminating at an opening. The oscillating unit is swingably connected to and disposed within the housing. The oscillating unit includes a swing member, and first and second weighting pieces. The swing member includes a swing arm, and first and second swing blocks connected to the swing arm. The first weighting piece is carried on the first swing block. The second weighting piece is carried on the second swing block. The swing arm is swingable to move the second swing block to block and unblock the opening.