The article is devoted to discussing the solutions of electoral law to the Constituent Sejm, one of the most important electoral regulations for the history of modern Polish state. It presents the specific character of its main solutions, in that the decree concerned the territory, which for the most part was not within the power of the emerging Polish state. It was also shown that the voting took place at different times and some of the Sejm deputies did not come from the elections. The influence of the indicated solutions of the electoral law on the further development of constitutional law in Poland was also presented.