The rice-Cnaphalocrocis medinalis (Guenee) system was studied based on the principles and methods of system sciences to seek possible ways or strategies for pest population control. A conceptual model describing interrelated activities among different generations of C. medinalis (Guenee) and their natural enemies was designed and implemented through differential equations or function formulas. The dynamics of C. medinalis (Guenee) and natural enemy population density were simulated and analyzed respectively using STELLA. The results indicated that trends of both C. medinalis (Guenee) and natural enemies’ populations in six pest-control scenarios differ in their peak values and occurrence time. A considerable quantity of natural enemies was essential to the effective control of occurrence and development of C. medinalis (Guenee). Introducing a number of natural enemies to rice fields at the early period of insect pest occurrence is recommended for enhancing the control of C. medinalis (Guenee) during the late growth period of paddy rice.