According to the principle of atmospheric pressure altitude measurement in pilotiess aircraft

the composition and the working principle of digital measuring system are introduced

and the method of data processing used by computer in measuring system and error analysis is discussed.On the basis of these

the design of field programmable gate array（FPGA） chip in atmospheric pressure altitude measuring system in pilotless aircraft is put forword

and the inside structure drawing and working flow of FPGA are given.The feasibility of the design is validated by emulation.Because the time of data processing of FPGA is about 6 μs

the problem of poor real time performance in atmospheric pressure altitude measuring system of high speed pilotless aircraft is solvesd effectively.