The excretory system should be taught through constructivism so as conceptual understanding could be built well, and students could apply their knowledge in daily life. The research aims to find out the influence of a learning model of Cooperative Integrated Reading and Composition (CIRC) based on scientific approach (Cirsa) on conceptual understanding of excretory system. The methods used include quasi-experiment with pre-test and post-test control group design. Instruments used are conceptual understanding tests of excretory system referring to Bloom's revised taxonomy of C1 to C6 consisted of 12 question items that are valid and have high-reliability categories. The research is conducted in 11th grade of Mathematics and Science of a senior high school in excretory system subject. Learners involved in the research consist of 68 people. Sampling technique uses simple random sampling. The results of Kolmogorov-Smirnov test and Fisher test obtained that conceptual understanding excretory system data are normally distributed and homogeneous. The results of hypothesis testing on normalized gain and effect size calculation indicate that there was an influence of Cirsa learning model on conceptual understanding of excretory system which cateqorized into effective. Based on the research findings, it is expected that excretory system learning could be taught to learners using Cirsa learning model.