The invention relates to construction methods, in particular to a tunnel (7) construction method suitable for mountain land. The tunnel (7) construction method comprises the following steps of A, river closure, B, grouting, C, blasting, D, waterproofing arranging, and E, recycling of a material used in the step A. According to the method used in the invention, the steps are simple, the construction period is short, the cost is low, the tunnel (7) restores earth surface rivers after demolition of a diaphragm wall (5), and damage to the ecological environment is small; and aiming at the situation of crushing of overlying rock mass, the target stratum non-equal density modification technology and the tunnel (7) excavation arch part presplitting and blasting technology are combined to reduce disturbance on surrounding rock and guarantee construction safety.