The article addresses an issue of structuring the natural science school education content and substantiates the trends of its modernization under orientation at the all-round development of a personality. The features of implementation of the crosscutting lines into the content of the basic courses reflecting socially and personally important ideas and relating the relevant key competencies are determined. The necessity of strengthening the competence orientation of the natural science component of the content of basic secondary education is substantiated. In particular, it is stressed the topicality of orientation towards a system of values and competencies that determine the ability to successfully operate in practical educational and life situations, to be responsible for his/her actions in nature and society. It is proved that updating of content is a condition for successful deployment of crosscutting content lines. Their mastery by students involves the use of methods and forms of instruction that maximize the activity, competence and personally oriented approaches aimed at solving practical learning and life situations, stimulate formative learning. The authors underlined that the increase of attention to the effective component of the content of education, strengthening its role in the formation of subject and key competences, specifying the state requirements to the training level of general education students in the educational field Natural Sciences are the main directions of modernization of school natural science education content.