The aim of this study is to reveal experienced primary school teachers' pedagogical content knowledge (PCK), sub-components of PCK, and their possible interactions with science teaching. To this aim, a multiple holistic case study design was used. The research used a comprehensive PCK model consisting of 5 categories and 28 subcategories to reflect the knowledge base of teachers. Among the volunteered teachers, four experienced primary school teachers were randomly selected for research. Data triangulation, which utilizes interview, observation, and document analysis together, along with a subject matter knowledge test (SMKT) developed by the researchers, was used to explore teachers' PCKs in-depth. According to the results of the research, it was concluded that instead of making standard generalizations about teachers' PCK, explaining the situation over sub-categories and making comparisons on the basis of teacher competencies can guide our PCK understanding. Due to PCK's complexity and depth, several results were obtained in this study. One of the basis result of the study, the PCK category, in which experienced primary school teachers are the best compared to other categories, is "pedagogical knowledge" which is consistent between teachers and within each teacher's own levels of sub-categories. The weakest PCK categories of teachers were "knowledge of assessment in science" and "curriculum knowledge of science," this situation also leads to inadequacies in using appropriate contemporary learning-teaching processes, strategies, alternative assessment methods and rubrics. Therefore, the PCK model of the research can be recommended as an explanation guide for future studies.