Abstract-A large-scale wireless sensor network constructed in terms of two-tiered architecture, where cloud nodes take charge of storing sensed data and processing queries with respect to the sensing nodes and querists, incurs security breach. This is because the importance of cloud nodes makes them attractive to adversaries and raises concerns about data privacy and query result correctness. To address these problems, we propose an efficient approach, namely EQ (efficient query), which mainly prevents adversaries from gaining the information processed by or stored in cloud nodes, and detects the compromised cloud nodes when they misbehave. EQ can not only achieve the goals of data privacy and integrity preserving but also ensure the secure range query without incurring false positive. For data privacy preserving, EQ presents an order encryption mechanism by adopting stream cipher to encrypt/decrypt all sensed data such that a cloud node can only process issued queries over stored data in the encryption domain. For data integrity/completeness, we manipulate a data structure of XOR linked list (X2L), which allows a querist to verify the integrity of retrieved data via the socalled verification information, i.e., neighborhood difference in a storage-efficient manner. We demonstrate the feasibility and efficiency of EQ via experiments conducted on TelosB prototype sensor platform running TinyOS 1.1.15 and comparisons with state-of-the-arts.