Even though maize is a staple crop in Ethiopia, an ineffective postharvest management system results in a considerable postharvest loss. This loss occurs along the value chain from harvest to storage. This study aimed to investigate the impact of threshing, and storage conditions on the physicochemical and insect infestation of maize grain during storage. Freshly harvested maize grain of BH-540 variety was used for the study. Maize was threshed at three moisture content levels (13,17, and 23%) using two threshing methods (hand & mechanical). Maize grains after threshing in all methods were dried to safe storage moisture content (13%) using a solar bubble dryer. The dried maize grains were stored in five different bags (Purdue Improved Crop Storage bag, GrainPro, ZeroFly, woven polypropylene bag with plastic liner, and woven polypropylene bag) in a room for 6-months. Each post-harvest loss indicator parameter and the Physico-chemical properties of the grain were measured over 6-months, at an interval of 3-months. Minitab software (version 19.2) was used to analyze the data. The highest broken kernel was observed on maize grain threshed mechanically at 23% moisture content (44.00%) and the lowest was observed on maize threshed by hand at 13% moisture content (2.73%). There were significant changes in the physical and chemical composition of stored maize grain across different types of storage bags as the storage period increased. Overall storage bags and threshing methods, maize threshed mechanically, and stored in woven polypropylene bag had the highest weight loss (5.45%). Throughout the 6-month storage period, the highest grain damage was observed on maize threshed mechanically at 23% moisture content and stored in a woven polypropylene bag (20.06%). Maize moisture content during threshing, threshing methods, storage bag types, and duration all had a significant effect on total adult live insects, with the maximum observed for maize threshed mechanically at 23% moisture and stored in woven polypropylene bag for 6-months (227.67 adult/kg). Threshing moisture content had a significant effect on germination capacity, mold growth, oil, and protein content. In general, hermetic bags outperform woven polypropylene bags in terms of keeping desired physical and nutritional properties and reducing losses due to maize weevil infestation. Keywords: Hermetic bags, Insect Pest, Maize, Postharvest loss, Threshing methods