Concentration is the way of procurement, and bidding is the means of procurement, so centralized procurement can be completed through bidding, and bidding procurement can be centralized or decentralized. Bidding is a highly specialized comprehensive application of technical, economic and legal means, which requires strict procedures and specific skills, which makes a specific contractor have all kinds of knowledge and skills. Therefore, in government procurement, it is usually divided into self-bidding and entrusting professional institutions to conduct public bidding. \x0d\ Bidding procurement refers to the process in which the purchaser, as the tenderee, puts forward the conditions and requirements of procurement in advance, invites a number of enterprises to participate in bidding, and then the purchaser selects the best transaction object at one time according to the prescribed procedures and standards, and proposes the bidder with the most favorable conditions to sign the agreement. The whole process requires openness, fairness and merit. Bidding is one of the most common ways of government procurement. \x0d\ Centralized procurement refers to the centralized procurement of goods, projects and services in the centralized procurement catalogue. Centralized procurement includes centralized procurement by institutions and centralized procurement by departments. Catalogue belongs to general government procurement projects, and centralized procurement agencies shall be entrusted to purchase on their behalf. For projects with special requirements for this department and this system, centralized procurement by departments should be implemented. Compared with centralized procurement, it is called decentralized procurement. \x0d\ For government departments, centralized procurement can effectively make up for the shortage of decentralized procurement, and through centralized bidding, procurement times and procurement costs can be reduced; Centralized procurement, high transparency, convenient supervision and low supervision cost; The centralized use of procurement funds can achieve economies of scale, which is conducive to the realization of national government procurement policy objectives.