Harvesting is considered to be the final stage in the technology of cultivating giant clover for seeds. Effective periods and ways of harvesting are able to reduce the losses of crop yield up to 5-10%. Due to this fact, the paper considers effective technological harvesting when cultivating tetraploid giant clover for seeds as very relevant. Field experiments on investigation of the effect on Kudesnik tetraploid giant clover seed productivity caused by the way and period of harvesting were carried out in 2013-2015 on the sod-podzol clay loam according to the methods of experiments. Cold and humid vegetation periods in 2014 and 2015 contributed to the highest seed productivity (174.5 kg/ha) of Kudesnik tetraploid giant clover which was received while single-phase harvesting with preliminary sowing desiccation in the phase 75-80 % of Red glomus when forming density with following parameters: glomus number - 1204 un/m2, the number of glomus on the stalk - 4.5 un, seed mass from a glomus - 0.023 g. The highest effect produced by glomus productivity on the crop yield of Kudesnik clover seeds was observed in 7-10 seeds only. The authors admit that 90-95 % of glomus brown discoloration was preferable in two-phase harvesting. Biological crop yield of clover seeds was 14,56 g/m2 when there was free choice of pollen plants; no pollen plants (under isolator) - всего 0.16 g/m2. The highest biological properties (energy of growing and laboratory viability) were observed in seed material received during late harvesting whereas at the same time rock-solid seeds were observed. The research found out that high mass of 1000 seeds was observed in seeds received while 75-80% red glomus desiccating with further direct harvesting with a combine (2.65 g) and two-phase harvesting in the late period (2.58 g).