Thick-walled cylindrical vessels are used widely in petrochemical and power plants. New additive manufacturing technology has made it possible to make FGMs. This research studies the creep analysis in the cylindrical FGM pressure vessel by considering three models and yield criteria. Also, the governing equations were extracted by considering the FGM models, and for determining creep stresses, the partial differential equations, were solved. Norton's equation is used to determine creep strain rates. The advantage of the exponential model is that in the inner radius for all n radial and circumferential creep strains rates have a constant value that is maintained by increasing the internal pressure up to 400 MPa. The graphs are smooth, and their values tend to zero in the outer radius. The changes of creep strain rate in terms of n in different internal pressures for the exponential model in the inner radius of the vessel show that increasing n from -4 to 0, these parameters have a reduction to the form of an exponential function, and the slope of the graph has the highest value at 360 MPa. تفاصيل المقالة