Background: Food insecurity and hunger contribute to physical, psychological, and social effects. The relationship between food insecurity and negative consequences on health has been confirmed in multiple studies. The present study aims to identify food security and its association with some demographic factors in children and their parents. Methods: In this descriptive-analytical study, 1688 children aged 3-6 years were selected using cluster random sampling in 15 health centers in Qazvin, Iran. Results: The results showed that 855 participants (50.7%) had food security, while 552 (32.7%) had food insecurity without hunger, 242 (14.4%) had food insecurity with slight hunger, and 37 (2.2%) had food insecurity with severe hunger. A significant correlation was observed between parental education level and food security (P < 0.001). Also, there was a significant correlation between the children’s body mass index (BMI) and food security (P < 0.005). No significant difference was observed between BMI, mother weight before delivery, and children’s sleeping and wake-up time in both groups. However, the birth rank (P < 0.01) and number of family (P < 0.02) in the secured group was significantly higher. The age of complementary feeding in the secured group was significantly higher (P < 0.06). Conclusion: Given that there is an association between birth weight, breastfeeding, parents’ education, and occupation with food security, it seems that pregnancy status and breastfeeding should be much more studied.