A flowmeter is applied to flow measurement for oilfield underground water injection. Two eccentric axial holes are arranged in a casing, a transverse hole is arranged on the casing, penetrates through a flow passage perpendicularly, and is communicated with the bottom of an electronic bin. A cylindrical sensor base is fixed in the transverse hole, a hollow target rod is fixed in a center hole of the sensor base, and the other end of the hollow target rod is positioned in the flow passage and provided with a target piece. A solid target rod is fixed in a center hole of the hollow target rod, a vortex target is fixed at the outer end of the solid target rod, and an electric vortex probe is arranged on the upper portion of the vortex target and perpendicular to a center axis of the solid target rod. A cylindrical plug is fixed in the transverse hole of the casing in a threaded manner and provided with a radial hole, and the diameter of the radial hole of the cylindrical plug is equal to that of the flow passage. The flowmeter has the advantages of compact installation structure and capabilities of realizing accurate measurement of flow in high-pressure environment and meeting requirements of underground flow measurement upon volume and pressure bearing capacity.