Investigating of trainees’ occupational skill gap is one of the primary tasks of instructors to enhance trainees’ ability at every training center. The main purpose of this research was to investigate factors that affect occupational skill development in garment technology trainees in Debre Markos Poly Technique College. The researcher raised questions at the beginning of study about the major factors that affect garment training in relation to trainees, in relation to Study College, about the instructional time appropriateness to cover the course efficiently and the attitude of trainees’ towards garment training. The design of the study was descriptive, which helps to describe factors that affect occupational skill development. The data gathering instruments were questionnaire, observation, document analysis and focus group discussion. The data were gathered from 50 garment trainees. These samples were selected using comprehensive sampling method. The method of the study was mixed approach (both quantitative and qualitative method). As it is stated in the research questions and gathered data shown, majority of trainees rarely measured body parts properly, unable to made the designs/patterns, most trainees’ had a problem of cutting based on the designs, had problem of sewing with proper designs. About the effect of training materials also, most very essential materials like Ironing boards, Seam rippers, cutters and Computers were not available. The other materials were not found in different sizes for different purposes and the observed materials were not standardized and rare to practice one to one for trainees. The instructional time was not enough to practice the skill. The trainees’ attitude towards garment technology, as shown in the data, most of the trainees did not like garment technology training and they believe that the training could not bring positive impact on their life. Generally, most essential materials were inadequate, not standardized and not found in different sizes. Most trainees’ had poor attitude towards the training and they had poor confidence in using the available training materials.