Accreditation system plays an increasingly important role in international trade and government supervision. ISO/IEC 17025 and ISO/IEC 17020 are the general requirements for accreditation of testing laboratories and inspection institutions respectively, and both stipulate the capabilities of laboratories and inspection institutions and the impartiality and consistency of their activities. Aiming at the possible ambiguity in the operation of ISO/IEC 17025 and ISO/IEC 17020 systems, this paper compares and analyzes the similarities and differences between them from the aspects of “human, machine, material, method, environment” and management elements. It aims to help testing/inspection personnel to clarify ISO/IEC 17025 and ISO/IEC 17020 standard requirements, improve management level and technical ability, standardize testing/inspection activities, and enhance market credibility and competitiveness.