The invention discloses a runner gate structure of an injection mold with an in-mold insert. The runner gate structure includes a gate, a runner and a diaphragm. One end of the gate is in communication with a mold cavity and the other end of the gate is in communication with the runner, the runner, near the gate, adopts a fan-shaped runner, the edge of the diaphragm is located above the runner, the fan-shaped runner is inlaid with an insert, the insert is of a long strip structure, and one side of the insert abuts against the edge of the diaphragm. The runner gate structure, by setting the insert structure at the runner gate, replaces the slider or inclined top structure used in a traditional IML mold, the existing mold structure is effectively simplified, the weight of the runner is reduced, the plastic consumption is reduced at the same time, and unit price of a product is lowered.