Learning mathematics is very beneficial in the student’s future lives. However, there are many students who have difficulties in learning mathematics in each of their education levels, so it is important to review the stages of student’s cognitive thinking. Considering the stages of thinking at primary school ages, mathematics material needs to be presented in a concrete way. One of them is the Concrete-Pictorial-Abstract (CPA) approach. Seeing the importance of mathematics and the students’ difficulties related to their cognitive development stages, teachers need to be continuously equipped with mathematics teaching competencies to achieve learning goals. But, seeing this need, online training was carried out with the Concrete Pictorial Abstract learning method for teachers who teach elementary mathematics to achieve professional teacher competence in teaching and later it will have an impact on students’ mastery of mathematics. The purpose of this study is to see the impact of training with Concrete Pictorial Abstract on the professional competence of elementary school mathematics teachers. The method used in this study is quantitative research by comparing the professional competence of elementary school teachers in teaching mathematics before and after being given online training in CPA. Then training will be provided for one school year in accordance with the personal development teacher’s schedule. The subjects of the study are sixth grade mathematics teachers at Lentera Harapan schools throughout Indonesia. The results of the study show that online teacher training can improve teachers’ professionalism in teaching mathematics.