The main biomass carbon measurement parameters of the tree layer,including biomass expansion factor(BEF),biomass conversion and expansion factor(BCEF),root to stem ratio(R),and wood basic density(WD)were analyzed.The results showed that the carbon measurement parameters of Pinus tabulaeformis plantations in northern Hebei were BEF of 1.521,BCEF of 0.833 t/m3,R of 0.207,and WD of 0.468 t/m3.There were significant differences in BEF and BCEF values between different forest age groups.R and WD were no significant.The results were lower than the recommended values at the national level,which indicating the forest biomass density in this area was lower.It was recommended to increase the number of regional biomass plots in the future to improve the accuracy of carbon sink assessment.At the same time,measures to improve forest quality should be taken to increase forest carbon sinks.