Abstract: In the ID-based crypto system，user’ public key is decided by his ID which is not distributed by CA.This way has solved the problem of public key’s storage and management.In a threshold proxy signature，the power of signature is distributed to a signature group which can prevent the abuse of the power.This article introduces an ID-based threshold signature scheme which uses bilinear parings.In addition，an analysis is given about the relevant security of this scheme.And this scheme can also withstand the conspiracy attack.