The invention discloses an axial oil inlet structure of a gear case. Inner volume cavity with an inward opening and a radial oil hole with an upward opening are arranged in an end cover, and a lower opening of the radial oil hole is communicated with the inner volume cavity; one end of a work shaft extends into the inner volume cavity, a lubricating oil channel is eccentrically arranged in the work shaft, and the oil inlet end of the lubricating oil channel is communicated with the inner volume cavity; the work oil channel is arranged at the axial center of the work shaft, a balance valve is arranged at the oil inlet end of the work oil channel and is arranged on the end cover in a penetrating manner, and one end of the balance valve is communicated with the work oil channel. According to the axial oil inlet structure of the gear case, the lubricating oil channel and the work oil channel are arranged on the same side of the work shaft, the back valve is pushed by the pressure difference between lubricating oil and work oil, so that the mixing of the work oil and the lubricating oil is avoided, the length of the shaft does not need to be increased, and the complicated structure needed by the radial sealing is not needed. The axial oil inlet structure also has the advantages that the structure is compact, the assembly and the maintenance are convenient, the adaptability is strong, the manufacturing cost is low, and the like.