Resources and environment carrying capacity, which is one of the main basis for the evaluation of principal function area division, reflects the adaptive relationship between resources and environment, human economic and social activities, and is also one of research and practice focuses in principal function area division. In this paper, we analyzed the meaning of present researches about resources and environment carrying capacity, the related indexes and their evaluation methods, and discussed the practice about resources and environment carrying capacity calculation and evaluation in principal function area division at provincial level. The existing index system and index calculation methods were created on the base of natural properties only, and ignored the impact of human activities on natural resources and environment, and can't fully characterize the actual carrying capacity of resources and environment of the evaluation area. In order to solve these problems mentioned above, we proposed to use air, water, land, energy and ecology as five main natural constraint elements of regional development, and evaluated each element from both resources and environment attributes about its development potential. In addition, we improved the index calculation methods through increasing the contribution of human science and technology component over the existing method, i.e. calculation of total amount of nature. Based on the above ideas, we took principal function area division at provincial level as an example to propose a resources and environment carrying capacity evaluation index system, which contains 5 elements and 16 indexes, on the base of analyzing the existing 5 resources and environment related indexes. Finally, "water environment capacity" index was selected to explain the improved methods of index calculation. This index system and index calculation method can be used in some related filed also.