PIP: Fertility model theories play a significant role in fertility analysis and planning. How to build fertility models under different conditions so that they can be applied more accurately in policy comparison and fertility projection has always been an important topic in demographic analysis techniques. On the basis of previous research results and with the help of a queue-period fertility rate matrix, the methodology is studied. The methods and significance of building fertility models under different conditions, the use of a cohort-period fertility matrix in fertility projection and analysis, and a case analysis are included. Specific methodology is discussed for building fertility models with complete, incomplete, or no fertility data. It is argued that the non-least-square method in building Brass-correlated fertility models is better than the least-square method. A rationale of that claim is offered.