In order to solving the errors of frequency measurement, and put forward the method of best frequency-divider to realize high-accuracy frequency measurement. It aimed at the problems of missile measurement, in the end the design was simulated on the QUARTUS platform by the two principles of best frequency-dividing method based on equal-accuracy frequency measurement. Finally it was proved that the best frequency-dividing method inherited the advantages of equal-accuracy frequency measurement, it was able to measure frequency within 100 MHz, and it also bettered the disadvantages of equal-accuracy frequency measurement whose open time of counter is fixed.