The lateral energy fraction in hall is an important objective factor of spatial impression, and it is usually simulated by computer simulation. We first used MKH800 to measure the lateral energy fractions at the corresponding positions of a real hall. Then, we established a 3D model of the hall with ODEON 6.5 to simulate the lateral energy fractions at the receiving points. Finally, the simulated lateral energy fractions were compared with the measured ones. The comparison results show that the simulation values are larger than the measured ones. The deviation of the simulated values is small in the front part of the seating area, and it is large in the middle and back part of the seating area in front of the stage. The reason for the deviation is that the diffusion coefficient of ODEON is not related to the areas' character, and the diffusion coefficient of each frequency band can not be separately defined in this software. Therefore, in order to accurately predict the indoor acoustics, it is recommended to use architectural acoustic scale model to measure lateral energy fractions.