In the present article, while providing a brief definition of the claim and its legal bases, it has tried to specifically address the source of the employer's claims of the contractors of construction projects based on the texts in the Iranian and world civil literature and especially the source of claims in the Tehran regional electricity company (trec), we have studied and weighed them with critic technique and analyzed the results and prioritized the factors of claim bases by multi-criteria decision making Studies show that in Tehran Regional Electricity Company, the source of inaccuracy of the initial estimate of the work performed by the employer (D4) with a total current of 0.6574 is the main source of claim in this company. After that, the exchange rate changes and the jump in the price of materials (B5) are in the second place. As a possible source, the topic was included in 33 questions and, incidentally received a high rating. However, the employer can reduce the vulnerability of the project by placing clauses in the contract, such as adjusting the exchange rate, etc., to the detriment of the project. If we ignore issues that are beyond the control of the employer, such as unforeseen events and sanctions that rank third. The low accuracy of estimating the appropriate time for the project by the employer agents with a net total current of 0.5216 is in the fourth place. In addition, the best way to negotiate was identified between the ways of reviewing and handling the claims made by the contractors (dispute resolution), and mediation, judgment and referral to the judicial authorities based on the research background are in the next ranks and only a small percentage. (About 6%) of the disputes have been settled by the court.