Two field experiments were carried out at the experimental farm (Ghazala Village), Faculty of Agriculture, Zagazig University, Sharkia Governorate, during 2016/2017 and 2017/2018 seasons to study the influence of three planting densities, (28000, 35000 and 46666 plants/fad.) three levels of N fertilizer (80,100 and 120 kg/fad.) and two levels of potassium fertilizer (24 and 48 kg k₂O/fad.) on yield and its attributes as well as quality of sugar beet grown in clay soil. Results of combined analysis illustrated that, decreasing planting density from 46666 to 35000 or 28000 plants/ fad., significantly increased root length, root diameter and fresh root weight g/plant; on the other hand the highest planting density (46666 plants/fad.) produced higher sucrose, extractable sugar percentages, sugar and recoverable sugar yields/fad., than low or medium densities. Raising N fertilizer levels significantly affected yield and its attributes as well as quality of sugar beet. Where, the results of the combined analysis indicated that, each increment of nitrogen fertilizer level from 80 up to 120 kg N/fad., cm was accompanied with a significant increase in root length, root diameter, fresh root weight/plant, root and recoverable sugar yields/fad., but significantly decreased sucrose (%). Data of combined analysis also revealed that application of 48 kg K₂O/fad., significantly increased root yield attributes i.e., root length root diameter (cm), fresh root weight g/plant, sucrose, extractable sugar percentages, as well as, root and recoverable sugar yields ton/fad., compared with supply of 24 kg K₂O/fad. Interactions between the studied factors (according to the combined analysis) indicated that the highest root yield (ton/fad.) was achieved when sugar beet was sown with the highest plant density of 46666 plants/fad., and fertilized with 120 kg N/fad. As well as, the highest value of root diameter (cm) was achieved under the application of 120 kg N/fad., and addition of 48 kg K₂O/fad., while, the interaction between planting densities and potassium fertilizer levels had no significant effects on all studied traits.