Abstract: The high accuracy of Fabry-Perot (F-P) etalon interval d has a very important influence on the interference measurement. Based on F-P interference imaging information, combined with the local subdivision principle of the peak coordinate and the regression of circular equation, in particular, a new method of virtual plane pixel subdivision and signal smoothing was applied, and the concentric ring diameter D_i was obtained accurately. Then the accurate calculation of the decimal part and the integer part of the interference order was realized, and the measurement of the interval d by excess fraction method with three-standard wavelengths was completed. In addition, the influence of subdivision and non-subdivision on measurement results was analyzed. With the virtual pixel subdivision, the interval d is (2 009.961 91±0.000 06) μm, and (U_ε/k₀) is 9.8×10^-7.Experiments verify the effectiveness of pixel subdivision method, providing effective ways to improve the accuracy of interval d.