The invention relates to a method of and equipment for preparing an analysis sample (2) for a continuous on-line analysis. According to the invention, a sample material (5) is taken by means of a sampling arrangement (4) from a material flow (24) that contains solid matter and liquid, whereby the sample material (5) is fed into a chamber (6); a layer of material (10), which contains coarse solid matter, depositing in the lower part of the chamber, and a layer of material (8), which contains liquid and fine solids, being separated from the sample material in the upper part of the chamber, whereby at least part of the material (8), which contains fine solids, is moved to the lower part (9) of the chamber (6), from where the analysis sample (2) that has a higher solids content than the sample material (5) is removed.