Aiming to accurately measure the dynamic weighing system of straw bale in small square baler and reduce the influence of vibration caused by ground jolting and mechanical transmission on the measuring accuracy of straw bale. The influence mechanism of different working speeds of baler and the start or stop of the tractor PTO on the pressure noise signal and angle noise signal of dynamic weighing system of straw bale was analyzed by an experiment. When the sampling frequency of the system was 40Hz, the signal frequency of pressure noise was mainly within the range of 0.1~16Hz. The frequency of the angle noise signal was mainly in the range of 3~4Hz and 16~17Hz. The working speed of baler was positively correlated with the noise signal strength. On the basis of signal analysis, the signal processing method was researched. First of all, aiming to eliminate the influence of singular value about the original signal, the double threshold based on the rule of 3σ method for signal preprocessing was carried out. Then piecewise linear interpolation was used to supplement the vacancy point. Finally, a Butterworth band stop filter was designed to eliminate the noise signal and further improve the filtering precision. The field test results showed that the relative error of straw bale quality prediction was between -4.15% and 4.17% after the signal was processed by the method. The relative error of straw bale quality prediction was between -5.15% and 5.08% after the signal was processed by the method of average filtering. The signal processing method was better than the average filtering. Moreover, this filtering method was more adaptable and met the actual production needs.