The effects of different plant space on the population structure and yield formation with mechanical transplanting of mid-season indica rice Huiliangyou 5 were studied. The results showed that the theoretical yield of Huiliangyou 5 reached 11 228.8 kg/hm2 and its components were coordinate with the machine-transplanted space of 14 cm and fixed row space of 30 cm. The increase and decrease of the stems and tillers were smooth and the ineffective tillers decreased. The production of dry matter from heading to mature period increased with 44.8% to total dry matter production. The basal internodes were shortened and the stem diameter increased for decreasing the lodging risk of Hui Liangyou5 and fulfilling potential of high yield with mechanical transplanting.