This chapter provides a comprehensive overview of fundamental performance testing methods for dust collectors, supporting effective selection, inspection, and maintenance. First, it outlines testing items, preparation conditions, operating conditions, and appropriate locations and sampling points for accurate performance assessment. Next, the chapter describes measurement of critical gas parameters, including gas composition, temperature, density, humidity, and dew point, and explains the significance of each parameter in evaluating dust collector performance. It then addresses methods for measuring dust collector resistance, helping readers recognize energy efficiency and identify potential issues. The chapter also details techniques for assessing dust removal efficiency, including dust sampling, concentration calculation, and efficiency determination. Lastly, procedures for measuring leakage rates and conducting dust collector airtightness tests are presented, with practical guidance on minimizing air leaks to maintain optimal system operation.