Effects of genetic and environmental factors on yield and seed size of 10 sugar beet singles crosses were evaluated using randomized complete block design with four replications. Experiments were carried out in Ardabil, Firouzkooh, and Karaj, Iran, in 2013-14. Plant materials included 10 CMS lines crosses with one O-type. Combined analysis of variance for placesshowed that sugar beet seed yield was influenced by both genetic and environmental parameters. Some of the environmental parameters had significant effect on seed size. Cold regions including Ardabil and Firouzkooh showed higher standard seed production (%) compared with temperate region, Karaj. In addition to environmental differences, significant differences were also observed among CMS lines in relation to standard seed production (%) (singles crosses). Considering standard seed size, results showed that the weight (%) of seed with standard sizes was influenced by both genetic and environmental parameters. Five biophysical seed characteristics and 6 environmental parameters collected from synoptic station. Canonical correlation study showed a relatively high and significant relationship between biophysical seed characteristics and environmental parameters and formed five canonical groups, among which only the first and the second groups were statistically significant. From the total variance of seed biophysical parameters, 48% of the total variance of seed biophysical variation was predictable by the first and the second canonical variables of environmental  parameters. The first canonical variable function indicated the reduction of both standard and above standard seed size yields in comparison with under standard seed size. Considering of high positive construction coefficients for sunny hours and minimum and maximum temperatures, it can be concluded that the standard and above standard seed size yield reduced under Karaj environmental conditions with long sunny hours, higher minimum and maximum temperatures and lower altitude compared with Ardabil and Firouzkooh environmental conditions.