Tree biomass models are essential tools for estimating forest carbon stocks and assessing ecosystem services,and building biomass models for regionally dominant tree species is of great significance for calculating biomass and carbon storage more accurately.Based on the measured biomass data of 90 sample trees of typical coniferous tree species in low mountain and hilly region of Chongqing,this study developed single-variable and two-variable biomass models for Pinus massoniana and Cunninghamia lanceolata(including whole-tree,stem,crown,aboveground and belowground components)as well as Cupressus funebris(including aboveground biomass,stem and crown components),and the model accuracy and applicability were evaluated.The results showed that:1)The determination correlation coefficients(R²)of the two-variable biomass models for Pinus massoniana,Cunninghamia lanceolata(aboveground,belowground,and whole-tree),and the aboveground part of Cupressus funebris were all greater than 0.930.The mean prediction errors(MPE)were less than 2%,which met the precision requirements of LY/T 2258—2014.2)Compared with the three coniferous tree biomass models applicable to the Chongqing region in GB/T 43648—2024,the developed two-variable biomass models for aboveground and belowground parts of Pinus massoniana and Cunninghamia lanceolata showed improvements in both model precision and estimation accuracy,and making them more suitable for biomass calculations within Chongqing.The findings will provide valuable data support and methodological reference for regional coniferous forest carbon stock assessment and refined forest management in Chongqing and the broader Southwest China region.