Abstract: The shock attenuating check valve of LRTH764 X/Y-350/6-4 type, a newly developed multiple purpose check valve while keeping the conventional functions, is characterised by shock attenuation through the damping of hydraulic cylinder, and low pressure tight sealing. With a minimum sealing pressure of 0.003 MPa(factory testing pressure), it can be installed in the bypass for pigging, while maintaining the operability for reverse pumping. It is integrally casted, with its both ends welded to pipeline. Both soft and hard sealing materials are available for valve clack and cup, with the soft material being made of oil resistant acrylonitrile-butadiene rubber, high temperature rubber or reinforced polytetrofluorine as required by the customer. Equalizing feature for rearrangement of counter-balance moment is available in the valve, resulting in less flow resistance loss after openning the valve clack. Two year industrial applications demonstrate such facts as no sealing leakage, stable clack openning and no inner shocking. It is also proved by manually operating valve clack that the valve is stably fixed, easy to operate, and applicable in pipeline systems handling crude oil, oil products, or non-corrosive fluid. Also introduced are the design procedure and the strength and process calculations of its main part.