The present invention relates to a method for installing a land wind power generator by using lead rails, and the method includes the steps of: locating a lower support having an insertion protrusion, a horizontal stepped surface, and a ground anchor, under the ground; locating a pair of posts of a tower crane and a cage for each post at the horizontal stepped surface of the lower support, ascending a nacelle assembly and an overhead crane, and locating an intermediate support by means of an outside crane; and locating the lead rails along the ground and the front surface of the intermediate support and ascending an upper support along the lead rails by means of the overhead crane. Next, after a nacelle base, a support frame, the lead rails, and the tower crane are disassembled from the located positions, a plurality of propellers connected to rollers located inside a rotary part of the nacelle assembly are lifted by means of a winch and are inserted into a plurality of coupling grooves of the rotary part. The method of this invention has relatively low installation costs and provides more effective and rapid installation processes to advantageously reduce the construction period.