Written legal texts (so-called normative legal texts) are also indispensable for the study of the history of Great Moravia. The most extensive of them is the Great Moravian Nomocanon, which is a translation of its Byzantine original, while the author has significantly narrowed the original text. Most experts dealing with the history of Great Moravia assume that the author of the translation was Methodius himself. In this paper we try to determine when the translation of Nomocanon was conducted. The previous papers stated that the translation was carried out at the beginning of the Byzantine mission in Great Moravia. In this paper we present the hypothesis that the translation of Nomocanon was probably conducted only in the final phase of Methodius’s activity in Great Moravia. This hypothesis is supported by the timing of the necessity (and urgency) of its translation in practice, as well as by the historical events of the fight between Wiching and Methodius.