The study aimed at detecting the performance of the teachers of science in the tenth grade in the implementation of the tools of continuous assessment and the difficulties they face in the Sultanate of Oman, also it aimed to recognize the impacts of variables such as (Social class, specialization, qualification, experience and number of works, hops conducted Using analytical descriptive approach to suitability according to the nature of the study and its objectives). The researcher prepared two tools, the first is a form of analysis of the level of performance of science teachers who are teaching the tenth grade The second is a questionnaire to identify the difficulties faced by science teachers when implementing the tools of continuous assessment, and after verifying the validity of the tools and their consistency, they were applied to the study sample, where the sample consisted of (70) teachers in the province of Muscat, And (73) teachers in Dakhliya presence using the questionnaire, (51) teachers from Muscat Governorate and (65) teachers from Dakhliya Provence using the performance level analysis tool. The results of that the level of performance of the teachers of science in grade 10 in the implementation of tools for continuous assessment was of the average level, while the degree of difficulties encountered in the implementation of continuous assessment was a medium degree of difficulty in general, while the level of performance in the order of aspects enables the science teacher to apply tools : The tool of short tests came at a high level, followed by the tool of writing works at an average level. In third place came the tool of practical performance at an average level, and came the highest degrees of difficulties facing the performance of science teachers according to the aspects of difficulties measuring tools for the continuous assessment in: administrative aspects and training related to continuous assessment. The least difficulties were in the understanding of the procedures of continuous assessment. In the light of the result, the study suggested a number of recommendations like: the need to lighten the administrative load from teachers and the workshops should be more effective and practical.