Legal basis: Article 12 of the Measures for Tendering and Bidding of Construction Projects requires that the construction project is under any of the following circumstances, and with the approval of the examination and approval department specified in Article 11 of the Measures, the construction bidding may not be carried out: (1) It involves national security, state secrets or emergency rescue and disaster relief and is not suitable for bidding; (two) belonging to the use of poverty alleviation funds to implement the work-for-work relief needs to use migrant workers; (three) the main construction technology adopts specific patents or proprietary technologies; (four) the project built by the construction enterprise for its own use, and the qualification grade of the construction enterprise meets the engineering requirements; (five) the original winning bidder still has the contracting ability of the affiliated small-scale project or the main storey-adding project of the project under construction; (6) Other circumstances stipulated by laws and administrative regulations.