As a critical device for assessing the size and number of particles in a fluid, the accuracy of the measurement results is critical for several industry sectors. The factors that may affect the light-blocking particle counter and sensor in the measurement process were analyzed, and the corresponding countermeasures were put forward, including optimizing the calibration method, improving the installation conditions, strengthening the sample handling and optimizing the analysis process. The error of particle counters in practical applications was help to reduced, the accuracy of analysis results was improve, and help related industries to better assess fluid pollution degree and quality by these measures.