Security of a multiple-level relay-eavesdropper channel is studied, and the rate-equivocation region and achievable secrecy rate are derived in a discrete memoryless channel and a Gaussian channel, respectively. In particular, we analyze the achievable secrecy rate in two-level relay-eavesdropper and one relay-eavesdropper channels in the Gaussian channel under a limited power, and compare their achievable secrecy rate by simulation. The results show that a higher achievable secrecy rate is achieved in the multiple-level relay-eavesdropper channel when the relay node is far away from the source node. Therefore, security of the multiple-level relayeavesdropper channel is generally better.