The measurement of catecholamines in human body fluids is requested frequently for the differential diagnosis and monitoring of pheochromocytoma. The methods in most clinical laboratories focus on high-performance liquid chromatography coupled with electrochemical detection, which suffers from high background noise, low sensitivity, and poor separation. We reported and developed a robust high-throughput liquid chromatography tandem mass spectrometry method in routine clinical laboratories for the measurement of urinary catecholamines for diagnosis of pheochromocytoma. The method was validated for consistent linearity, good recovery (88-112%), excellent stability and low carryover. Intra- and inter-assay precision values for catecholamines were all below 3.35 and 4.83% respectively. Dilution linearity was investigated with satisfactory linearly dependent coefficients (r > 0.9988). The reference intervals were obtained from 310 results derived from patients in which the diagnosis of pheochromocytoma was excluded. This method was successfully used in our laboratory. The clinical characteristics of patients have been explored with satisfactory sensitivity and specificity. Therefore, we have developed a reliable assay for the liquid chromatography tandem mass spectrometry measurement of catecholamines in a routine clinical laboratory. The assay requires a small volume of urine, and all analytes are measured simultaneously. The assay is rapid and reliable to be executed, offering the potential for routine clinical laboratories.