Paper quality is controlled in the production of a paper web, where paper stock is fed from the headbox of the paper machine onto the wire section, whereby the paper stock is formed into a paper web. The headbox flow rate and consistency are measured from the paper stock fed into the headbox, and the water quantities removed on the wire section during the formation of the paper web are measured on the wire section. In the method, a filler distribution model is established, into which data on the wire section geometry, measured headbox flow rate and consistency and on the water quantities removed on the wire section are entered, and the model is used for establishing an estimate of the filler distribution, and the running values of the paper machine are adjusted on the basis of the estimated filler distribution.