Abstarct: Abstract Today, with the growth of the population in the world and the industrialization of countries and the change of human lifestyle and high consumerism, the production of waste in all its types is growing rapidly. This causes the environment to be endangered and the health of people in the society to be endangered. Therefore, it is important to pay attention to waste management more than ever. Therefore, this research was carried out with the aim of identifying and prioritizing obstacles to sustainable urban solid waste management baxsed on the multi-criteria decision-making approach under z numbers in the metropolis of Mashhad. and seeks to improve the process of sustainable urban solid waste management by identifying these obstacles. In the first step, after studying and reviewing the past literature and interviewing the experts, 125 obstacles were identified and these obstacles were categorized into 7 sections and 42 obstacles were filtered using the fuzzy Delphi method. In the next step, the weighting of the criteria was done using Swara's method under z numbers, and in this step, the category of socio-cultural obstacles with a weight of 0.3745 received the highest weight and the category of human resources obstacles with a weight of 0.0326 received the lowest weight. Also, in the section of sub-obstacles (non-cooperation of citizens) in the category of cultural and social obstacles with a weight of 0.3725 and (weak regulatory frxamework) in the category of inappropriate regulations and legal frxamework with a weight of 0.3245 and (lack of domestic capital) in the category of financial and financial obstacles with a weight of 0.3744 and (lack of integrated approach and system for solid waste management) in the category of information and knowledge sharing problems with a weight of 0.381 and (inappropriate media) in the category of technical obstacles with a weight of 0.3823 and (ignoring or underestimating the side effects of intervention) in the category Operational obstacles or weaknesses with a weight of 0.4479 and (personnel have a large workload) in the category of human resources obstacles with a weight of 0.5991 were assigned the highest weights.