Background: Studies have shown that vitamin D deficiency can be related to the occurrence of preeclampsia. Objective: The present study was conducted with the aim of determining the relationship between the serum level of 25-hydroxyvitamin D and preeclampsia and its related risk factors among obese or overweight pregnant women. Methods: This cross-sectional-analytical study was conducted on 83 pregnant women referring to comprehensive health service centers in Makoo city. Anthropometric indices and biochemical factors including vitamin D serum level, glycemic indices and lipid parameters were investigated in these women. In addition, the food intake of the participants was evaluated using an FFQ. Results: The results showed that there is a direct correlation between vitamin D serum level and dietary fat level (r=0.269, p=0.007) and high-density lipoprotein (HDL-C) (r=0.478, p<0.0001). Also, there was an inverse correlation between serum vitamin D level and pre-pregnancy body mass index (r=-0.625, p<0.0001), systolic blood pressure (r=-0.592, p<0.0001), diastolic blood pressure (r=-0.592, p<0.0001), fasting blood sugar (FBS) (r=-0.511, p<0.0001), proteinuria (r=-0.422, p<0.0001), triglyceride (TG) ( r=-0.225, p=0.020), total cholesterol (TC) (r=-0.428, p<0.0001) and low-density lipoprotein (LDL-C) (r=-0.602, p<0.0001). Conclusion: There is a direct relationship between dietary fat intake and serum vitamin D level. There is also a positive correlation between serum levels of this vitamin and serum HDL-C. On the other hand, there is an inverse relationship between the serum level of this vitamin and systolic blood pressure, degree of proteinuria, pre-pregnancy body mass index and FBS, TC and LDL-C.