Abstract: Abstract In order to build up a rapid and efficient method to measure the commonly used parameter of flax fiber fineness（Nm）, the application of microscopic image technique was proposed for this research. Flax fiber fineness was measured with traditional gravimetric method, and flax fiber diameter（d）was scanned and measured on a microscopic image instrument. Both data of fiber fineness and fiber diameter were calculated and analyzed by statistic software SPSS 3.0, 6 regression equations about the correlation of flax fiber fineness and fiber diameter were modeled. The suitable regression equation was Nm=159＋2.505×105/d2（Correlation coefficient r=0.801**), there was a good correlation between fiber diameter and fiber fineness. Thus flax fiber fineness could be, nearly at the same time calculated based on this equation once fiber diameter was measured automatically on machine. F-test and t-test results showed that there was no significant difference between traditional gravimetric method and this new method. There were also good precision, repeatability and reproducibility in confirmatory experiments among 4 measuring institutions where this new method was put into use.

Key words: foax fiber line density, fiber diameter, microscopic image technique, regression model, optimization and confirmation