Child malnutrition accounted by poor dietary diversity is common in developing countries contributing for child morbidity and mortality. It also has an impact on child growth and development. Almost all nutritional related problems are preventable by implementing infant and child feeding strategies. The first two years of life are particularly important to reverse the nutritional problems by achieving dietary diversity feeding.The study aimed to assess dietary diversity and its associated factors among 6-23 months old children in Sinan , Northwest Ethiopia.We conducted community based cross-sectional study among children aged 6-23 months in Sinan from February 16 to March 10, 2016. Random sampling technique was used to select 740 samples. Data on children's dietary diversity of the last 24 h were collected through interview of mothers. Data were entered into EpiData version 3.1 and analysis was performed using SPSS version 20. The bivariate and multivariable logistic regression analyses were done to identify the independent factors associated with sub-optimal dietary diversity among children aged 6-23 months.Seven hundred thirty six samples were included in the analysis with the response rate of 99%. Optimum dietary diversity was observed in 13% children. The dominant food groups consumed were grains. Availability of media sources at household [Adjusted Odds Ratio (AOR) = 2.77 (1.65-4.68)], availability of cow milk in the household [AOR = 2.39 (1.31-4.35)], women's involvement in decision-making at household level [AOR = 2.07 (1.02-4.20)], institutional delivery service utilization [AOR = 2.40 (1.24-4.67)], receiving assisted delivery service [AOR = 2.36 (1.12-4.98)], receiving postnatal care [AOR = 2.07 (1.18-3.63)], distance far from the health center [AOR = 3.11 (1.66-5.83)] and meal frequency being four and above [AOR = 3.31 (1.53-7.18)] were associated with dietary diversity.This study concluded that optimum dietary diversity among children aged 6-23 months in Sinan is low. Meal frequency is positively associated with dietary diversity. Women involvement at household decision making improves dietary diversity of children. Ensuring maternal health service utilization can contribute for better dietary diversity of children aged 6-23 months. Large scale an interventional based research has to be conducted.