Smart grid, deemed as the next generation of power grid, can efficiently monitor, control, and predicate energy generation and consumption. However, the frequent collection of users' consumption information in smart grid may reveal user's privacy, and the tampering of smart grid communication may also impair the data integrity, subsequently affecting the precise monitoring and controlling at the control center. In this paper, to address the aforementioned challenges, we propose a lightweight data report scheme for smart grid communications, which can achieve privacy preservation and data integrity simultaneously. Specifically, an efficient pseudonym identity-based privacy-preserving report approach is proposed for the control center to obtain the fine-grained usage data of all the users while protecting user's privacy. An online/off-line hash tree-based mechanism is also designed to check and assure data integrity of communications. Because of the shifting of most time-consuming computations to off-line phase, the online process is very fast and efficient by performing merely the lightweight bottom-up hash tree verifications to check all users' data integrity concurrently. Furthermore, a topology-independent data report architecture is also structured, which is adaptable for dynamic residential users to spontaneously form clusters and efficiently report data in flocks. Extensive performance evaluation demonstrates that the proposed scheme can achieve less communication overhead and dramatically reduce computational cost in comparison with the existing schemes. Copyright into two phases. One is off-line phase (during the report intervals) and the other is online phase (at report time point), which uses the pre-stored results in off-line phase to report usage data efficiently. Specifically, the main contributions of this paper are threefold.Firstly, a lightweight pseudonym identity-based privacy-preserving data report approach is proposed. Different from the existing data aggregation schemes, in which just the sum usage data can be obtained by the control center (CC), the fine-grained usage data of all the users can be obtained by CC in privacy-preserving way. Thus, provided that user's privacy is not revealed, with the detailed information, the whole system can be monitored and controlled more efficiently by CC. Secondly, an online/off-line hash tree-based authentication and data integrity verification mechanism is designed. Most of the computations of the smart meter with limited resources could be pre-processed in off-line phase. Furthermore, source authentication and data integrity of all the received usage reports can be checked simultaneously by performing the bottom-up hash tree verification procedures. Finally, a distributed and autonomous data collection architecture is structured. The users in the neighboring areas can form the cluster dynamically and flexibly, which makes the data report to be topology independent. And extensive performance evaluation demonstrates that the proposed architecture can achie...