This research for: 1) to study the current situation and problem in KM, 2) to develop the KM Model, and 3) to evaluate the finding usage of the KM Model for developing the Internal Quality Assurance of Educational Opportunity Expansion Schools. There were 3 Phases of research implementation. Phase 1: the current situation and problem in KM, was studied. Phase 2: the KM Model, was constructed, investigated, revised. Phase 3: the findings of usage in the KM Model for developing the Internal Quality Assurance of Educational Opportunity Expansion Schools. The research instruments for data collection were: the Questionnaire, and the Interview Form. The statistic using for data analysis included the Mean, Standard Deviation, and Percentage. The research findings found that: 1) The current situation and problem, found that were 7 Steps of implementation in KM including: the goal setting, the role determination, the knowledge construction, the shared learning, the knowledge selection, and the conclusions in body of knowledge, and the problem of KM, in overall, was in "High" level. 2) The KM Model, found that were 7 Steps of implementation in KM including: the goal setting, the role determination, the knowledge construction, the shared learning, the knowledge selection, and the conclusions in body of knowledge, and the delimitation of 8 aspects of Internal Quality Assurance. The findings of investigation in the KM Model, by all of 7 experts, found that the Mean Value was in "High" level. 3) The findings of evaluation in usage of KM Model, found that the Mean Value of testing after implementation of KM (posttest), was higher than before implementation of KM (pretest) at .01 significant level. The administrators and teachers had satisfaction in of KM Model, after the usage, found that it was in "High" level.