In the article the necessity of using mathematical modeling as the simulation method for solving problems at mathematics lessons in primary school is proved. The aim of the article is to prove that using the modeling method should perform a leading role in the formation of skills to solve problems, allows to achieve quickly high results in learning and mathematical development of junior pupils, makes them more productive in learning activities. It is emphasized that simulation takes a leading role in shaping the skills to solve problems. Modeling in the primary school enables to form skills of modeling different situations, events, actions, learning projects. The results of the simulation can be built schemes, graphics, lists, algorithms, charts, formulas, designated certain badges that help to solve mathematical calculations. Process modeling facilitates the development of theoretical thinking of primary school pupils. During the simulation the children improved overall techniques of mental activity, such as analysis, synthesis and comparison, contributing to a more productive educational activity of junior pupils. Using the simulation has: educational value – it helps to learn many of the questions in theory; educational value – contributes to the development of memory, attention, observation; practical value – the speed and accuracy of calculations. The authors show the stages of simple problems modeling using different models. Existing programs of mathematics require from children self-dependence in solving textual tasks. Each graduate of primary school should be able to record the task of the problem succinctly, illustrating it with drawings or diagrams, justify each step in the analysis of the task and its solution, check the correctness of the decision. Indeed, the intellectual level of children is different and it is impossible, without considering their age and personality, to teach how to solve any task on a specific pattern. We must choose different methods of work on the task for students with different levels. In this case at the mathematics lessons you should use several kinds of models to the same textual task. It will ensure that every child feels that he/she is able to solve this problem (is in «a situation of success»). Experience shows that widespread use of the modeling method in primary school creates a solid foundation for further study of mathematics.