A method for forming polymer microparticles is disclosed. The method comprises spraying a liquid comprising a thermally-gelling polymer from a first orifice of a nozzle into air to form gelled microparticles, and collecting the gelled microparticles with a collecting device. The nozzle is positioned to have a central axis of the first orifice at a tilt angle in a range from about 10 degrees to about 170 degrees relative to a direction of gravity. The collecting device comprises at least two collecting units at different distances from the first orifice of the nozzle in a horizontal direction perpendicular to the direction of gravity. Each of the collecting unit is loaded with a liquid collecting medium. A system for forming polymer microparticles is also disclosed.