This text is mainly to discuss the factor of deviation in the measurement surveying the dynamic droplet. Estimate the volume of the droplet from the piezoelectric droplet generator by using the program which can integrate boundaries of the droplet. Set up a droplet-observation system to make images of the sequence of drop formation and derive data from designed software. This work will analysis the droplet and output the boundaries parameters for the integration program. Discuss the deviation by comparing the estimated volume with the average volume of collected droplets. The different droplet sizes in different deviation measurements are also discussed here. And we expect that this research could bring us advantage for estimating droplets in the future.