With black masterbatch as the experiment object, experiments on dense phase pneumatic conveying were carried out in the self-build multifunctional pneumatic conveying facility. By comparing experimental data with the result of theoretical model calculation, the law of pressure loss before and after bending was studied. The study finds that: after the material is sent out from the bin pump, it needs to go through stable pressure and stable flow to reach a stable conveying state;based on the existing model, the pressure drop model modified by combining the experimental results can better predict the pressure drop of elbow, and the prediction error is less than 15.7%。