The properties of As-doped HgCdTe epilayers grown by Te-rich LPE were investigated. The Hall measurements showed that the electrical parameters varied greatly with the samples even though they were grown under the same conditions. If the epilayers are assumed homogeneous, Hall parameters cannot be interpreted well theoretically. By using the secondary ion mass spectrometry (SIMS) and temperature dependent Hall measurements, the accumulation of arsenic atoms was observed on the surface of the HgCdTe epilayers after the Hg-rich activation annealing at high temperature. The arsenic atom concentration of the accumulation layer is 1~2 orders of magnitude higher than that inside, which introduced a nonuniform distribution of acceptor AsTe in HgCdTe epilayer. Based on the characteristic of arsenic atom distribution, a simplified double layer model was applied to describe the distribution of the acceptor in HgCdTe epilayer. Hall parameters of the epilayers can be explained well by using the above method. The concentration and activation energy of acceptor are obtained.