Since the access control grain is not enough fine while users share resource during e-government cloud cross-domain access, a cross-domain access control scheme based on user's classification was proposed. In this scheme, a typical cloud computing access control mechanism——Identity and Access-control Management (IAM) was adopted, the assertion attribute authentication based on user classification was implemented, the obstruction caused by heterogeneity during resource sharing was also eliminated, and a fine-grained cross-domain access control mechanism was provided. Finally, a cross-domain system for cloud computer environment based on Shibboleth and secure component keystone of OpenStack was built, the feasibility of the scheme was proved by the test of comparing the tokens between inter-domain and outer-domain of a user.