The invention provides a comprehensive risk priority number calculating method for architecture. Three risk factors (the appearance frequency, the severity degree and the discovery index) in FMEA are evaluated in the mode that fuzzy numbers are utilized in software architecture in a leveled mode; the appearance frequency and the discovery index are determined through component complexity and expertise, and the weights of different risk factors are distinguished through the conception of information entropy; through the conceptions of a positive ideal solution and a negative ideal solution in a TOPSIS method, a more reasonable and accurate risk priority number rank is obtained; in this way, a comprehensive software-failing mode risk factor evaluation technology for the architecture is achieved. By means of the comprehensive risk priority number calculating method, at the initial software design stage, developers are helped to find out potential design defects in a system, and therefore the subsequent software development quality is guaranteed.