Driven by high-speed airflow, sand particles are easily carried into gathering pipelines and equipment during shale gas extraction. Sand accumulation in rectifiers may form a blockage, which will directly affect the accuracy of the downstream flow rate measurement. In this study, an experiment platform was established to analyze the velocity range of the easily blocked rectifier and the rectifier's blocking form. The variation of measurement error caused by the blockage was also analyzed. The minimum pipe downstream of the rectifier was calculated based on the experimental verification of the accuracy of the numerical model. It was found that when the inlet velocity was in the range of 3 m/s and 8 m/s, the rectifier was more likely to be blocked. Moreover, two holes in the middle and lower parts of the rectifier were blocked. The maximum deviation of the flow rate measurement error was 3.32% between the blocked and unblocked rectifiers. The length of the straight pipe increased by 300 mm to restore the flow field downstream of the blocked rectifier to a symmetrical and stable state. It provided a reference for setting the distance between the rectifier and the flowmeter. This work also provided an idea for further research on the accuracy of the flow rate measurement in the gathering and transportation of shale gas.