In this paper, we first investigated some important properties of high temperature ESR of doped (B and P) and undoped a-Si1-xCx:H and a-Si1-xNx:H alloy films. The ESR measurements were continuously performed in high temperature annealing process. Our experimental results show that: (1) For B-doped a-Si1-xCx:H and a-Si1-xNx:H films, a ESR absorption line can be decomposed to a broad (g1 = 2.005) and a narrow (g2 = 2.010) ESR absorption lines, g1 and g2 correspond to the contributions of Si dangling bonds and of holes in the valence band tail states, respectively. (2) The drop of hole density in the valence band tail states is faster than Si30 with rising temperature. The hole density in the valence band tail states is further larger than Si30 when temperature is low. However, the contribution of Si30 is the main one when temperature is very high.