This study aims to introduce the judicial declaration, and its importance in terms of scientific and practical, in the Omani Law of Civil and commercial, by answering the following questions: 1) What is judicial declaration? 2) What data should be available in judicial declaration paper? 3) Who are the persons may be announced? 4) What types of judicial declaration pre-and post-judgment? 5) Who has the right to invoke the invalidity of the declaration? 6) What are the conditions in which the right falls to invoke the invalidity of a judicial declaration? 7) What are the consequences of the invalidity of a judicial declaration? The researcher used in this scientific study, the analytical method, in addition to legal principles, with reference to some form of judicial decisions, analysis of these texts, and theories to reach the objectives and the results of this study. In conclusion, the researcher reviewed the most important consequences of the study, with recommendations.