【Objective】Train wheel is a significant noise source in the rolling noise, and predicting its vibroacou stic behavior involves calculating the large scale acoustic problems. To improve the computational efficiency of wheel sound radiation, this paper introduces the Boundary Element Method with Adaptive Order (BEMAO). 【Method】The sound radiation of the wheel in free space was studied by using the combination of the finite ele ment method and the boundary element method. The BEMAO was used to calculate the sound power radiated by the wheel, the sound pressure at standard measurement point, and the directivity of the wheel acoustic radiation. Comparison was then made with the corresponding results obtained by the conventional boundary element meth od (CBEM) and the fast multipole boundary element method (FMBEM) as well as the computational time.【Result】The sound radiation obtained by three different boundary element methods are basically consistent, but the BEMAOis about 36 times faster than the CBEM, and 11 times than the FMBEM.【Conclusion】The calculation efficiency of the BEMAO is obviously higher than that of other boundary element methods, and remarkable ad vantages and good applicability are shown in studying the sound radiation from the wheel at high frequency. The outcomes of this paper can provide reference for calculations of large scale acoustic problems.