Background Scientific and systematic evaluation index system of soil and water conservation carbon sink capacity can provide basic data for quantitative analysis of soil and water conservation carbon sink capacity in a region, which is of great significance for guiding the implementation of soil erosion control measures, and providing information of soil and water conservation for the realization of carbon neutralization goals in China.

Methods Based on the mechanism, pathways and material performances of soil and water conservation carbon sink, referred to the carbon sink evaluation methods of terrestrial ecosystem, and combined with the basic data of soil and water conservation measures and their benefits, the technical route "soil and water conservation measures and their benefits (carbon sink material basis) → carbon sink pathways → material performances of carbon sink → carbon sink quantity"was proposed and adopted to analyze and clarify the evaluation index system of soil and water conservation carbon sink capacity.

Results The index system includes 5 primary and 11 secondarysoil and water conservation measures and their benefit indexes, as well as the corresponding carbon sink rate and organic matter content, such as soil and water conservation forest land, grassland, basic farmland, water retaining body and their benefits.

Conculsions The evaluation indexes of regional soil and water conservation carbon sink capacity proposed in this study areused to monitor, estimate and count the carbon sink function size of regional soil and water loss prevention and control measures and their benefits. On the regional spatial scale, they have the operability of synchronous implementation with statistical work and convenient data acquisition. In the dimension of estimation parameters, they have the spatial correspondence and accuracy between the location and number of observation points and the estimation results. The evaluation results can be used for analyzing of regional carbon sink capacity and its change trend, for evaluating of ecosystem quality and protection effectiveness.