The invention discloses a primary supporting concrete wet spraying method applied to a weak surrounding rock tunnel, and belongs to the technical field of tunnel construction. The method comprises thefollowing steps: an arc steel arch frame is mounted on a rock surface beforehand, and a high-pressure air gun is used for cleaning the rock surface; mortar wets a pipe, and is sprayed to the rock surface; a slump test is performed; a curve path is adopted to finish the concrete spraying of the rock surface in a partition mode: arch top-upper step left arch shoulder-upper step left arch foot-archtop-upper step right arch shoulder-upper step right arch foot-arch top-upper step left arch shoulder-lower step left arc foot-arch top-upper step right arch shoulder-lower step right arch foot; the arch top and arch foot construction is performed in a flow mode, so that procedures are tightly joined, and the construction efficiency and progress are improved; and the accelerator mixing amount in concrete in different areas is gradually increased from bottom to top, so that the concrete spraying disability is guaranteed, the material utilization rate is increased, and the construction cost is reduced. A wet spraying machine is used for operation; other equipment and materials have no need to be added; and constructors are simple and convenient to operate.