This paper proposed a curve matching algorithm for constrained systems. Different from the programs running in personal computer, the constrained system has less resource. Due to the limitation of cost, it is impossible to use high level hardware to produce the system. The engineer shall concern about the time complexity and space complexity seriously. Now-a-day, there are many consumer products using embedding system including remote controller, pedometer, scanner, digital camera …etc. The result of this paper is useful to reduce the product cost.