The stainless steel multistage deep well submersible pump (hereinafter referred to as "pump") is a new type of water-lifting device made using advanced and mature processing techniques. Equipped with a submersible motor, it replaces the traditional long-shaft connected deep well pumps and can operate fully submerged at a certain depth underwater. It features a compact structure, excellent performance, high efficiency and energy- saving capabilities, small size, lightweight, stable operation, and ease of installation and use. Inside the pump, a flexible spherical check valve is installed to prevent reverse flow when the pump stops and to protect the pump from water hammer impact in the pipeline.