Abstract: The traditional weft detector is unable to make a comprehensive analysis of the large amount of measured data due to the limited function of its microprocessor.For this reason,based on the virtual instrument technology introduced by the American National Instrument Co.,an innovative weft detector is developed in which a computer is used in substitution for the microprocessor and the bias weft data was collected by a data collecting module.Therefore,this detector can simultaneously implement the tasks of collecting,analyzing,and processing bias filling data.This facilitates the further research of the rule of skewing.Experiments have proved that on-time detection and data analysis of bias weft and bias bend of fabrics are accomplished by this weft detector,and the rule of skewing can be summarized.