Pregnancy is an important period of life that may put them at risk of decreased physical activity and a large percentage of women have little knowledge about exercise during pregnancy, and their performance is not good. Therefore, the aim of this study was an evaluation the effects of education on exercise performance of pregnant women. This research was a semi-experimental study. 272 numbers of the nulliparas admitted to the eight health centers of Semnan, Iran selected by stratified-cluster sampling method and were placed in the intervention and control groups. Classes for the intervention group were held once every one week in the eight sessions and the duration of each session, was one hour. Collection of data was conducted through Godin and demographic questionnaires and in order to its analysis, SPSS software was used. The results of this experiment showed that the groups of intervention and control, were similar in terms of the demographic characteristics. Before the intervention, in terms of exercise performance, there was no significant difference between the intervention and control groups. After intervention level of physical activity was mild (53.7%) in the training group, and was in lack of activity range (99.3%) in the control group. Statistical analysis showed that there were significant difference in physical activity of intervention and control groups (p = 0.000). Therefore, the final results of this investigation showed that educational classes of pregnancy exercise had a positive effects on the performance of pregnant women.