Abstract: The Quantum Science Experiment Satellite (QUSES) is the first satellite deployed successfully in nearEarth space for quantum scientific experiments in the world, in which experimental study on the fundamental questions of quantum mechanics can be done under the condition of a spatial scale about 500 - 2000 km. QUSES is performing a Quantum Key Distribution (QKD) experiment from satellite to ground station for testing of the global quantum secure communication network, and performing a Quantum Entanglement Distribution (QED) and Quantum Teleportation (QT) experiments with the purpose of testing the completeness of quantum mechanics theory at a sufficient spatial scale. The payload of QUSES is composed of a Quantum Key Transceiver (QKT), a Quantum Entanglement Transmitter (QET), a Quantum Entangled-photon Source (QES), a Quantum Experiment Control Processor (QCP) and a Coherent laser Communication Terminator (CCT). This paper introduces the technical scheme of QUSES, including the 
requirement analysis, composition, technical innovation, on-orbit status and prospect of development for the future.