The students with reading difficulties in primary school have difficulties in reading, compared to their peers, which makes them difficult in academic and everyday life. Therefore, it is necessary to provide early reading interventions before these difficulties become more serious. The purpose of this study is to develop a multimedia korean alphabet(Hangeul) reading instruction program based on UDL principle to ensure accessibility of various students and secondly to examine how this program affects the students’ reading ability. The results of this study are as follows: First, the UDL-based multimedia korean alphabet reading instruction program was developed based on the following three principles. 1.Based on the principle of representation, information in the program was presented in various representation methods using multimedia including visual-auditory stimuli, text to speech(TTS), and hypertext. 2.Various options were provided according to the principle of action and expression, so that the interaction between the learner and the reading program could be achieved. Appropriate feedbacks for the student were also provided during the learning process. 3.Based on the principle of participation, various means of participation were provided. The learning environment was designed so that systematic learning could be realized and continuous feedbacks were provided. Second, the UDL-based multimedia korean alphabet reading instruction program was applied to 3 students with reading difficulties in elementary school during 21 periods. As a result, the students' reading ability gradually improved, and the results of the post-test rather than the pre-test were improved. So the UDL-based multimedia korean alphabet reading program was effective in improving the reading ability of students with reading difficulties. This is because the UDL-based multimedia reading instruction program has improved reading ability of students with reading difficulties by providing information in various means of representation, providing various means of action & expression, and providing various means of participation.