The main cold damage occurs in germination and seedling growth stages. To examine the effect of cold stress effects on rice seedling growth was carried out a greenhouse experiments in Deputy of Rice Research Institute in Mazandaran (Amol) since 2010. The basic design was conducted a completely randomized with split plot factorial experiment in 3 replicates with different temperature levels (10, 13, 16, 32o C) and its duration (1, 2, 3, 4, 5 days) on five varieties of rice (Dialam, line 843, Tarom, Fajr, Shiroudi). The varieties were designed as main plot and and temperature levels and duration of thermal treatment in sub-plot. The seedlings were placed in normal growth conditions until the 3-2 leaf stage seedlings age (12-8 days) and then transferred to a growth chamber and were treated at 10, 13, 16 oC for 1, 2, 3, 4 and 5 day. After the treatment, four seedlings from each replicate were selected and growth characters such as height, seedling dry weight (dry weight of shoot + root), sensitivity index, leaf area and color were measured. Results showed that among the varieties, the stress intensity, stress duration and their interaction effects were a significant probability of 1% for all traits in the seedling stage in which reflects the severity and duration of cold stress on the varieties is discussed. Low temperatures were reduced, the growth rate of seedlings up to 10 -50% compared with control treatment. Low temperatures (10oC) were decreased new roots production and seedling dry weight in which 60% reduction compared to 32oc treatment. Temperature was caused discoloration of lamina and the color of the leaves of rice seedlings after exposure to cold stress conditions could be concluded, each variety is greener leaf color of seedlings with less damage and is more tolerant to cold. Tarom and Shiroudi varieties compared to other varieties moretolerant to cold stress, however, Fajr variety was more sensitive.