A flat bottom ball valve is provided in the present disclosure. According to an example, the flat bottom ball valve includes a valve body, a valve core, a valve rod, a bonnet and a flow path. The valve core is mounted inside the valve body. The valve rod is mounted on two opposite sides of the valve body, perpendicular to a liquid flow direction and capable of driving the valve core to turn over. The bonnet is movably mounted on the valve body and parallel to the valve rod. The flow path is defined inside the valve body and connects two ends of the valve body. The valve core includes a main body part, a connecting part formed by extending symmetrically from two sides of the main body part, an accessory defined on the main body part and a first mounting hole in the connecting part to engage with the valve rod. The valve core swings around the valve rod along a path above the valve rod and is capable of being hermetically engaged with the valve body to turn off/on the flow path. A horizontal center line of the main body part is parallel to a horizontal center line of the first mounting hole in the liquid flow direction of the flow path.