A 6000-meter depth rating remotely operated vehicle (ROV) for marine scientific research is developed at Shenyang Institute of Automation, China. The 6000-meter scientific ROV can meet the scientific needs of deep-sea environment parameter measurement, optical observation and sampling in the depth of less than 6,000 meters. Launch and recovery system(LARS), control room, power distribution unit (PDU), 7000m umbilical cable in a winch, tool room and elevator are parts of the 6000-meter scientific ROV system. 6000-meter scientific ROV subsea system comprises structural frame, buoyancy materials, sampling bracket frame, hydraulic power unit, thrusters, manipulators, cameras and lights. The sampling bracket frame can carry multiple ocean sensors and sampling tools, such as bio-box, push-core, biological sampler, water sampling bottles and sampling basket. Deep sea qualification trials of 6000-meter scientific ROV in Gagua Ridge during September 2017 to qualify system for deep sea exploration and intervention tasks. The ROV dived seven times, of which two dive depths are 6000-meter rating. The ROV maximum diving depth is 5611 meters, which is the deepest diving record in China's ROV. System performance feedback, in-situ oceanological parameters such as water sample, sediment sample and microorganisms were recorded during trials. This paper describes the development of the ROV and those equipments using advanced technologies and test results.