Abstract: Taking Chinese fir (Cunninghamia lanceolata), the most important coniferous species in southern China, as the study object, the compatible two-entry and single-entry (diameter at breast height-DBH, and diameter at root collar-DRC) volume equations, height-DBH regression model, and DRC-DBH regression model were established using the error-in-variable simultaneous equation approach. Based on the three height-DBH models and two DRC-DBH models, four compatible volume equation systems were established simultaneously, which were compared with six statistics. The results show that the compatible volume equation system composed of simple height-DBH model and DRC-DBH model is quite sound, the mean prediction error (MPE) of two-entry volume equation is 1.31% and the MPE's of single-entry equations based on DBH and DRC are 3.66% and 7.39%, respectively. The tree volume equations developed in this paper can be applied for volume estimation of Chinese fir forests under different circumstances.