Abstract: A 16-bit single cycle stack processor based on Forth programming language is proposed in this paper,the processor has a data stack and a return stack of 32 elements deep,and a Harvard structure storage system.The instruction set of it includes 29 instructions,all of which could be completed within single cycle.When implemented on Xilinx's XC5VLX110T FPGA,The processor could run up to 162.7M Hz.The paper first introduces the design principle,architecture and instruction set of the processor and then analyses the strategy of instruction single cycle execution.Finally,it presents the result of hardware synthesizing and software simulation and analysis of it.