Internal rate of return, a kind of important economic analysis index, is often used by evaluating economic feasibility for engineering. Substantively, estimating internal rate of return is to solve higher-order equation with one unknown. Due to its precision disadvantage, complicated calculation, and especially theories lacks, traditional linear interpolation is unsuited to do with these questions. Real Coding Accelerating Genetic Algorithm (RAGA), a new method, has overall optimization ability, less calculation quantity, adaptability to interspace size of the optimistic search variety, swiftly calculation and high accuracy. It can be used and proved to calculate internal rate of return effectually. [Nature and Science 2003;1(1):72-74].