Abstract: The study demonstrates the economic outlook of citrus production investment in Florida,U. S. A. by the GAMS simulation. Five basic factors of decision-making of investment in long term were drawn dynamically and quantitatively with simulation. These factors are: expected net invest-on-return, minimum competition price, maximum acceptable interest rate, optimized schedule for new citrus planting, earliest year of receiving positive profits (net present value). The results are benificial for investors to make their correct decision-making prior to investment.