Abstract: Combining with the PIC microcontroller,a controlling system for continuous testing apparatus of the fineness of cocoon silk was developed under the framework of virtual instrument from American National Instruments Company(NI) in LabVIEW developing environment.The system can automatically detect the end breaking of cocoon silk when reeling,control the processing of winding device,and also gradually push the bave during reeling by Hall sensor and PIC microcontroller.The problems of cocoon silk breaking while testing and the difficulties in comparing results between testing and weighting methods were resolved by the system.Experimental results indicated that the reliability and anti-jamming ability of the controlling system were good.