The invention relates to elevators and discloses a waterproof dustproof sun-resistant elevator for an existing building. The elevator comprises an elevator shaft, wherein the elevator shaft is internally provided with an elevator lift car and a traction motor; waiting doors are mounted on a side wall of the elevator shaft; the waiting doors are externally connected with corridors communicated withthe existing building; a machine room is arranged at the top of the elevator shaft; the bottom of the machine room seals the opening of the elevator shaft; a control cabinet is mounted inside the machine room; the control cabinet is connected with the traction motor through a signal line; a plurality of water discharge grooves are formed in the ground of the corridors; the water flowing directions of the water discharge grooves are perpendicular to extension directions of the corridors; the depths of the water discharge grooves are gradually increased from the middles of the corridors to twosides of the corridors; water discharge holes are formed in side walls of the corridors; the water discharge holes are communicated with the water discharge grooves. By optimizing designing of the machine room and the corridors, and optimally selecting wire materials, rainwater can be effectively prevented from flowing into the elevator shaft to cause elevator faults; moreover, dustproof and sun-resistant protection can be achieved for wires and components inside the elevator shaft.