The current research aims to study (the effect of strategy of analysis - synthesis duality in the collection of scientific fourth stage students and high-order thinking in Biology material). For evidence the objective of the research, the researcher formulated the following two null hypotheses: 1. There is no significant difference at the statistical level (0.05) between the average of scores of the experimental group students that will study according to the dualism strategy of analysis and structure and the average of scores of the controlled group students that will study according to the normal way in the collection. 2. There is no significant difference at the statistical level (0.05) between the average of scores of the experimental group students that will study according to the dualism strategy of analysis and structure and the average of scores of the controlled group students that will study according to the normal way to test high-order thinking. A current research was Identified by choosing scientific fourth stage students in the governmental diurnal secondary schools which obey to Baghdad education directorate / the first Karkh of studious year (2014- 2015), and among these schools the researcher selected Ajnadayn secondary of girls as a purposive sample. To achieve the aim of research, the researcher used experimental design a partial control, and was selected two divisions of the scientific fourth stage randomly, one of them represent the experimental group and another the controlled group. The sum of research sample was 69 students, 34 students of them in the experimental group and 35 students in the controlled group .The two groups of search were tested by four variables (the time age measured by months, scores of biology material in the test of end of the first course, the test of intelligence, and the scores of test of previous biology information) in addition adjust the other variables, also the scientific material was defined with the last five chapters of the Book of Biology which is scheduled to teach of studious year (2014- 2015). The behavioral objectives were formulated of these chapters and numbered 256 behavioral objective represented to six levels of Bloom's Taxonomy in the knowledge field (remember, absorbing, application, analysis, structure, and evaluation). The tutorial plans were prepared for the two groups of research and numbered 22 plans for each group. The researcher taught herself the two groups during the period of the experiment, which continued 11 weeks of the second semester of the academic year (2014-2015). With respect to research tools, the researcher used one tool for each dependent variable, as prepared collection test of last five chapters of the book of Biology of the scientific fourth stage consisted of 47 items represented the substantive questions, as well as the researcher adopted test of study in high-order thinking consisting of 30 items represented in the two types of questions: 15 objective paragraphs and 15 essay paragraphs, were checking the veracity of tools through articles on a group of arbitrators, have been applied to investigational samples one of them to see how clear paragraphs and time of answer and the other was for the purpose of test statistically analyzed by extracting Alsiakeomtraha characteristics, in addition to the extraction of the stability for both tests. After the end of the experiment, the two tools were applied on groups of search, then the students, answers were corrected and they were treated statistically, and the results were as the following: 1. There are statistically significant differences in favor of the experimental group in the collection test and the size of the average effect of the independent variable was (0.63). 2. There are statistically significant differences in favor of the experimental group in the high-order thinking test and the size of the average effect of the independent variable was (0.5). The results indicated that there is a positive effect of teaching by strategy of analysis – synthesis duality on the collection and the high-order thinking, and based on that the researcher put a set of conclusions, recommendations, suggestions.