Abstract: To address the requirement for evaluating the aerodynamic characteristics of spacecraft during interplanetary entry in the rarefied transitional flow regime, a novel bridge-function method balancing efficiency and accuracy is proposed based on the sine bridge function. Using the direct simulation Monte Carlo (DSMC) numerical results of the rarefied Martian rarefied as the basis, the effectiveness of this method is evaluated in detail. The results show that the proposed bridge function method can effectively assess the aerodynamic forces in the transition flow regime; compared with Lockheed's sine bridge function, the proposed method significantly improves the computational accuracy; compared with the Erf-log bridge function, this method can calculate multiple aerodynamic force coefficients in the transition flow region based on given single-point numerical results, achieving high computational efficiency. Additionally, the results are insensitive to the selection of the altitude for single-point numerical simulation, there by reducing the DSMC simulation workload and providing technical support for the rapid evaluation of the aerodynamic characteristics of vehicles in the transition flow region.