The invention provides a group data completeness verification method based on a proxy. The method comprises an initializing stage, a data outsourcing stage, a completeness verification stage and a group user member updating stage. According to the method, users (owners and users of data) of each group are helped in data block signature computing by introducing a proxy Proxy in a system model, whendata completeness verification is conducted by TPA, any identification information of group users is not needed, completeness verification can be conducted by using the public key of the proxy Proxy,and therefore the identification privacy of group users is effectively guaranteed. The data block signatures of the group members are calculated through the proxy Proxy, the private key of the proxyProxy is unknown, so that even the originally uploaded data block signatures which are revoked of the group members are still illegal, the data block signatures do not need to be computed through other group legal members again, expenditure is reduced, and dynamic groups can be efficiently supported.