Birth weight is a remains a major public health issue particularly in developing countries which is significant predictor of a child's susceptibility to childhood illness incidence and survival chances. According to BDHS (2014) in Bangladesh, 22% children are born with low birth weight. The purpose of the study was to investigate the factors that are associated with Child size at birth Bangladesh Demographic and Health Surveys (BDHS) of 2014 dataset. In case of bivariate analysis, Chi-square test is performed and observed significant relationship of child size at birth and educational qualification of woman and husband, wealth index, types of residence and division. Multiple logistic regression analysis has been employed to identify the associated factors with child birth size. This study revealed some variables that account significantly for children born below normal size. For not-normally born children, the possibility of normally delivered children has 0.25 times less significant than caesarian delivered child and residential status, economic condition, women's education, husband’s education level is statistically associated with positive direction for child size at birth. On the other hand, woman's body mass index (BMI) is not substantially linked to child size at birth, but thin mother has the greatest chance. This work will help to guide the people to address the issue of Low birth weight.